Impact of Technology - Collaborating Online Respectfully

Gaining support for a cause

Networks: from semaphores to the Internet

Spreadsheets

Programming essentials in Scratch: part I

Programming essentials in Scratch: part II

Design Vector Graphics

Computing systems

Development for the Web

Representations: from clay to silicon

Mobile app development

Intro to Python programming

Animations

Data Science

Cybersecurity

Representations: going audiovisual

Python programming with sequences of data

Physical Computing Programming

Computing

Y8 Computing

Key Stage 3

Year 8

UNIT

In this lesson, we will investigate the use of symbols to represent information (just like computers do) and relate this to human practice for centuries. We will prepare for exploring binary representations in the context of computing.

Across time and space

﻿Hi there, I'm Miss Alade, you're computing teacher for this unit, Representations From Clay to Silicon. In this lesson, you will need a pen and paper. Pause the lesson and get pen and paper. Also, remember to remove any distractions before you begin the lesson. In this lesson, you will uncover the problems we solve through writing. You will discover how computing is about solving these problems. Consider the question you've got on screen at the moment. I do not want you to answer this, but keep this in the back of your mind. If we can express our thoughts and feelings through speech or gestures, why then do we need writing? Right. So now you're going to have a task and this task is to examine some ancient artefacts from the museum. They're very, very old pieces of writing. Think about what they might be about. Now, do not worry about getting an accurate answer. This is all about you using some imagination and some reasoning. Pause the video and continue when you're completed. Well done. Good try. So what are these? These are artefacts, some of the oldest pieces of writing that could be found. Right, before we go into that, think about what happened thousands of years ago, a very long time ago, before writing ever began. There was what was called the oral tradition. It meant that everything we learnt was through speech, or was passed on verbally. So all of the art, all of the knowledge and all of the culture was being told or received verbally, but through storytelling. So there were ways of doing that through storytelling, through songs, through poems. So take, for instance, a king goes to battle. He comes back victorious. There will be a song for that king about the battle, documenting or telling the story about the event and how the king got to win. Now this song will be played or sung in the marketplace. And the song would go eventually from town to town to town. And that's how people would get to hear of the kings victorious success in battle. And you will tell stories, and you will listen. Entertainment was by storytelling, because there wasn't any television then. So it was all by oral tradition. And that's how we actually received information and communicated it. But think about what problems that might cause. Imagine you had a birthday party at the weekend, and it was some really, really, really great and awesome birthday party. And you got to school on Monday, and you told your friend about it. And then your friend told another friend you know, but this time put his own twist on it or her own twist on it. Now, that friend now tells somebody else, and it goes from person to person. Now imagine what happens at the end of the week. How might your story be the same? Now your story may not even be the same, it might have completely taken a different turn, and not really, really accurately tell what you observed or what happened that weekend when you had your birthday party. So, oral tradition had its problems in the sense that you cannot accurately remember everything that happened. So things got changed, as it moved from person to person or generation to generation. So as humans developed, there was a real need to communicate, not just orally, and to keep record and to preserve cultures and memories, and that's how writing began. Now, these writings are what we call cuneiform. And some of them date back thousands of years. So as far back as 3000 BC. So if we think back 3000 BC, before Christ, were 2020 AD, 2020 years after Christ, so that goes as far back as 5000 years ago. Now, these document, different events, different stories, which we're going to find out shortly. We know we can express our thoughts and feelings through speech and gestures, and even pictures. So using what you know now, can you think of reasons why writing might have been invented? Pause the video and unpause when ready to continue. So why do people invent writing? So we have seen from the previous section that oral tradition has its problems. We could not accurately preserve and/or accurately receive information because you could be hearing something else that someone's saying that's not what the person is intending to. So in ancient times, it was necessary to invent writing, so events and documents can be more accurate. So that way people could receive, store and communicate information more accurately than through oral tradition. So writing was used to keep records of taxes, buying and selling, document laws and agreements, and even record calendars. Now, in ancient times, you would have had roles such as farmers, fishermen, there would be kings, there would be astrologers, there were lots of temples, religious places of worship. And those temples have priests. They had prophets, and they had temple activities. So there was that need to document temple activities. And in some ancient piece of writing, there were cakes inscribed on tablets. And those cakes were cakes that were being given in temples. So all of those activities when necessary to record. Farmers needed to record how much harvest, how many bags of barley for instance, they harvested, how many bags of barley they sold. And also calculations would have been done for instance, that farmer would want to say calculate that or find out how many bags of barley left at the end of the week. So at the start of the week, the farmer might have had 10 bags and sold seven bags. So if he had 10 bags, and now there are seven bags, how many bags has he got left at the end of the week? So as you would have rightly listed and put down, it helps us store and remember information. And this information stored can be processed, and examine in the ways in which humans represent information. It helps us build on that vital understanding of how computers represent information also. You will see more representations which you're going to be examining. These are more modern, so they're more familiar to you. There are a few examples. The first you're going to see are these flags semaphores. So take a good look. And decide and think who decide what the sequences mean, and where might you use them. So these are flags for communicating. The next representation are hand signs. Again, this is something that would be more familiar to you. Who decide what the sequences mean and in which situation would you need to use them? Now we've got Braille. Again, this is familiar to you. Who decide what the sequences of symbols mean and in which situation would each of these be used? Now, this is our last representation for this section that you're going to examine. Who decides on these symbols? Where would you see these or use them? By all means, pause the video to complete your task, and when you're done, just continue. Right, going through the solution then. You would have seen quite a number of familiar representation such as the flag semaphores and sign language. And also, you would have actually recognised that some of the representations you came across also in this task, can be read by humans, and some cannot be read by humans, in other words can only be read electronically. Now, who agrees on these symbols? We have to agree on what they mean. There is no use actually having a sign language that isn't... That nobody else can understand and we all have our different meanings. So we have to agree what a particular type of information means. So for instance, what does A mean? So we'll have a common meaning across all representation. So A would mean something in flag semaphores and it would mean something in sign language, and so on and so forth. Going then on to the next question. How then would you use these? In which situation would each representation be used? We have seen that it really does depend. So, each representation is suitable for different types of scenarios. For instance, the sign language will be suited to communicating with those who cannot hear or communication at a distance. The flag semaphores also can be used to communicate at distances. And the bar code for instance can only be read by computers. So, information held there can only be accessed by computers. And we know also or you have seen rather, that information in computers is always represented in a form that the computers can conveniently process. Onto making meaning of symbols. There are two vital points to note here. The first one being that different sequences of symbols can represent the same thing. We have a series of representations that you can see and in each type of representation, a word or a symbol will carry the same meaning. So, for instance, we can have A and we can represent A in all of the symbols, sorry representation. So, for instance, as the symbol A will be present in Braille, it will also be present in sign language and also in semaphores. So, different symbols carry the same meaning. The other point to note is that the same sequence of symbols can represent different things. Take for instance the sequence of symbols D-A-B, DAB, it can mean several things depending on the context you use it. It can mean a kind of fish, or it can also mean a small amount or a skillful person, or it can mean musical notes D, A, and B. How does this link to computing? Why do you think people need to write information? You have travelled across time and space and have seen various representations. But before that, you started with learning what oral communication was all about. We saw the problems of a communication posed, and those problems have been easily resolved through the invention of writing. With writing, information can now be stored across time more accurately. That information can also be communicated across distances, and processed also. This sequences of symbols you've seen, can store any pieces of information. So whatever the information, it can be represented. You have also learned that computers also need to store, process and transmit or communicate information just like humans do. And computers also use sequences of symbols in ones and zeros to actually represent information. And we saw something called the ASCII coding scheme earlier. You have come to the end of this lesson. And during this lesson, you have learned that writing was invented to store information. Computers also use symbols to represent information too just like humans do. And symbols are used to communicate, but by humans and by computers. Patterns of symbols can mean anything we agree on. And you also saw that some representations are more convenient than others. It would be nice to see your work. So if you'd like to share your work with Oak National, please ask your parent or carer to share your work on Instagram, Facebook or Twitter @OakNational, with #LearnwithOak. Hope to see you next lesson.

In this lesson, we will learn how to encode, transmit, and decode short messages using a variety of coding schemes and communication medium (signals, light, sounds, holes in paper, etc.). We will understand that text representation uses sequences of symbols.


Lights and drums

﻿Hi there, I'm Sarah your Computing teacher for this unit representation. This is lesson 2 of 6, lights and drums, and you will be needing pen and paper to take some notes. So by all means pause the video to get yourself ready, get pen and paper, remove any distraction such as notifications then you will be good and ready to continue they lesson. So you can look on what you will be learning in this lesson. You will learn that characters can be represented as sequences of symbols. Examine examples of character coding schemes and measure the length of representation as number of symbols it contains. Take a look at this form. Here is a nice first task. Two friends live on huts opposite side of a great lake, a big lake. They have no wiFi or mobile phones in that part of the world. But they would like to exchange messages from a distance. Your job is to try and workout how they can do so. Pause the video and complete this task and when you have completed press play to continue. Right from lesson 1, you might remember representations used for communication across distances, such as flag semaphores or sign language, or perhaps you came up with with new examples, such as morse code or using light signals or may be you even devised a new system entirely for communicating across distances. There are forth amount of coding schemes out there but in this section you will only come across a handful of them. Coding schemes are ways of representing information that can be communicated across distances. In this first example, the Morse code, you will see that the coding schemes consists of dits and dahs or what we call dots and dashes. They can be generated by turning light on and off, tapping on object or by making sounds. This may be familiar to you actually. You may have seen this as well. The next coding scheme you see is called ASCII code. Which stands for The American Standard Code for Information Interchange. This is a way of representing texts and numbers in all electronic devices. It major for 7-bit code which represent characters and numbers on your keyboard. It uses binary digits 0 and 1 to represent as such as 7 numbers hence 7-bit code. The next coding scheme you see is International Telegraph Alphabet No.2 or the ITA2. It was widely used in telegraphy, and for the first time, telegraphy allowed messages to be sent by electrical signals or by radio waves without the need of physical transportation. In ITA2 each character consist of a code of 5 bits, and you can use it for long distance communication in what's called telegram. Coded telegram were printed out on punched paper tapes, in the form you can see on the screen before you. The next examples of coding scheme you see is the Bacon Cypher or sometimes called the Baconian Cypher, and this was invented by Francis Bacon in 1605. It's a way of encoding messages also consisting of 5 characters. Each character could be A or B. In this section you will learn how to transmit text messages. This process can be broken down into three steps encoding, transmission and decoding of messages. In this example we shall demonstrate to you the message or word has been encoded using Morse code which you have seen previously. I would need you much to watch this. But before that there is a diagram in front of you of the chart, using that, I'll play you the sounds of Morse code alphabet. See how many alphabet letters you can spot, perhaps they are 26, let's find out. I'll be needing this shortly, but let's find out. Right we are done, so how many did you spot? So onto the demonstrations, I'm going to use a torch. It's a variable light torch. So it contains some branson, maybe it's not the best example. But this will do. I'm going to demonstrate what the show, that's the light coming on. I going to demonstrate what dot is. So that's the dot. Ignore the clicking sounds, perhaps one doesn't click but torch does. So ignore the clicking sound. But just look for the light. So again, shots, so the long would be ... All right ,okay. So can we begin. You can use the chart in front of you to see or to sump to the letters that I'm going to be demonstrating. So I'll pause for a couple seconds in between and then to let you know, or to kind of demarcate letter from the other. So I will begin now, so my first letter will be? Next letter. Next form. Next form. And next form. Right so hopefully, that was very sweet. They were hopefully, you would have majored on what I have just demonstrated using Morse code how to communicate to you H-E-L-L-O, Which is hello. In this next example, I will encode using Morse code of four letter word. So listen carefully, I will demonstrate to you firstly what they should sound like. So this should be the long words, and the short. Okay can we begin, so the first word is, Let's start again.Think like I like that. So lets start again, so listen out for this one. Right I hope you got that.But we got just sent the message. Using Morse code, I want to use various mediums this time sound to transmit a message to you. I'll hope you enjoyed actually decoding those messages I've just transmitted to you as much as I have fond of encoding those messages. So that's task 1, you've got task 2, so your turn, pause the video complete the task and when you are done unpause. So here is the answer. Take a moment to pause and check your answer against this. So what you saw earlier on that activities was me demonstrating to you how to communicate at a distance. In other words, transmission. I transmitted to you to encoded words hello and code. Using two transmission medium, light and sound. We had agreement also, we agreed on the Morse code, as a coding system and there're rules, in terms for the rules of transmission. You knew what the sounds were supposed to sound like and you knew what the light was supposed to look like but for the dits and the dahs. Now that agreement between two parties, for communication is called protocol. Is like in English language, we have protocols or rules. For instance, I cannot construct a sentence without using a verb. Also we have communication equipment, we heard the sound which was like a kind of bell I was striking with the metal and we have the light, the torch. In our, on your screen you can see two communication medium also. The first on the top image, is a light, a big torch and the second, a drum. So drum here is to send messages also. Right, you might also have noticed during that activity, that there was a time I had to resend another word to you because it wasn't quite distinct. I might didn't strike the the dits and dots properly. So in communication protocol there is something called acknowledgement and there's something called retransmission. In that session I assumed you acknowledged even though I couldn't see you or hear you. The fact that you received both messages but also I was able to retransmit the message I thought was sent in error. Right, you have learnt that messages can be transmitted using various mediums. You have seen light being used, we've talked about sounds, we've talked about electricity, we've talked about paper and we've talked about all those such as drums. In my example to you, in the example you saw, 'hello' was transmitted for instance. The coding scheme used was Morse code, and the transmission medium was the torch, and we have the sound too. Now it's your turn to encode the message. So far you have to code the message, that I've encoded to you. You have seen various transmission medium in action, it's your turn task 3 to encode the the message 'kitty'. Pause the video and when you have finished, unpause. Well done, now check your answer. Well done. On to task 4, you have received the message and asked to get coding scheme. Now it's your turn to actually decode that message. Pause the video and unpause when you complete it. Well done. Now check your answer. You have learnt about coding systems and you have seen quite a few coding system. In the coding systems that you've seen, sequence series of symbols are used to represent a letter. Now in the coding system, any sort of information, can be translated into that coding system and stored, transmitted or processed. Now the physical form, or the choice of symbol that you choose to use, of whatever coding system, does not actually affect the information that is involved or transmitted. So examples of coding system we've seen, Morse code which uses dots or dashes. Braille, which uses raised dots or no raised dots at all. An ASCII that uses not and 1 or 0 and 1 and then you saw the coding system, the Bacon Cypher that uses a set of five letters consisting of As and Bs. So what is meant by representation length? You will see some examples to find out. In example 1, you've got kitty, using the encoding system Morse code. Original word five symbols of five letters, encoded message 11 symbols, four spaces. Another example, symbol reach the word kitty. Five symbols, five letters, the encoded message in the Bacon Cypher, 35 symbols. Another example, again the same original word with the same length, kitty, five letters with 35 symbols, in ASCII code. In our last example, we've got kitty again, 35 symbols for the same five original symbols. So this goes to show that different encoding systems, encoding the same original message will result in different length of encoded message, like you've seen. How the computer represent the information and why it doesn't matter. What is the link of representation to a computing? You have seen that coding systems uses symbols or sequences of symbols to represent a letter. You have also seen that the choice of symbol is irrelevant. As different coding schemes can mean or represent the same original message. You have also seen that in computing, the symbols used are 0s and 1s. In other words binary digits. In computing, every piece of information bit test numbers, images, sounds or representations in a series of 1s and 0s, and physical colour for that is electricity, electric current. You will examine some important questions to help you reflect on your learning during this lesson. The first one being, how can 0s and 1s be represented in the real world? Think about what you've seen in different activities. Pause the video and when you have finished with this thought, you can unpause. Well done, great answers. So we know that 1s and 0s can be represented in real world by using different types of medium. For instance we saw light, the torch for example used in Morse code. So I had on and off. We can also use holes on the paper like the punch cards, we can use sounds or electricity as we have in telegraphs or in the computer. So anything that has two states can be used. So well done. Next question, why have people invented so many different coding schemes? You can write down your thoughts down on the paper. Pause the video and when you have completed this exercise, you can unpause. Great answers again. So there are so many ways to communicate, so there is so many coding systems also. Coding systems have been invented to store information, and there're different schemes convenient for different purposes. For convenient asking to computer, braille to blind, we've got sign language for hard of hearing and the list continues. So you've learnt today how to encode, how to transmit and how to decode messages. You've seen various coding schemes and also you have learnt about transmission medium. You have also seen how problems can occur during communication. You have seen it's important to have communication rules called protocol and also it's important to acknowledge when you receive the message and also when there is an error there have to be a way of resending or retransmitting that message. You have also seen that every piece of information, encoded by in the computer is in 1s and 0s and the physical carrier can be electricity, paper as in hole punch, it can be light, magnetic orientation and the list continues. So well done, we've reached the end of this lesson and I wish to see you next lesson. If you'd like to share your work with Oak National, please ask your parent or carer to share on Instagram, Facebook, Twitter tagging @OakNational with #LearnwithOak

In this lesson, we will grasp what binary digits are by associating them with familiar sets of symbols such as letters and decimal digits. We will solve simple problems that reinforce the connection between (alphanumeric) information and its binary representation.

Binary Digits

﻿Hello, I'm Sara, your computing teacher for this unit representations. This is lesson three of six. You will need pen and paper to take notes. Remember to switch off notifications and remove any distractions before you begin. Pause the video, and when you are good and ready, we can begin the lesson. In this lesson, you will examine symbols, 0s, and 1s in more detail. Give these symbols a name, examine the significance of these symbols and discover why there's only two of them. There are different representations of cat. Which of these sequences of symbols is most likely to represent the text cat in a computing device? Give this a good think, pause the video, and have a good think. That's right, number two, because symbols commonly used in computing, are 0s and 1s and we've seen this earlier. We saw the ASCII coding system where every character on your keyboard is mapped to a 7-bit code of 0s and 1s. So who decided on the ASCII mapping between characters and binary sequences? Pause to think. I don't expect you to know the answer to this one, but have a pause. Right, it was American National Standards Institute. So what happened many years ago in the 60s, for instance, we had teleprinters, really simple machines. So you type in a master in one end, it gets transmitted and it comes out on the other end. The American standards Institute decided to come together to create a common code that everyone can use to interchange and send messages, so we're using the same language, so to speak. So they came up with the American Standard Code for Information Interchange. Now, you know that this is a 7-bit coding scheme. So it means that you can have from zero to one to seven. So you can have seven zeros, zero, zero, zero, seven times to seven ones. One, one, one, seven times, for your binary bit numbers. Now that meant you had 120 different possible characters. That was sufficient for all the characters on our keyboards, be uppercase and lowercase characters, numbers, and symbols. So this code soon became the standard in English speaking countries. Now, do you think this was the case in all every country or all of the countries? Yes, you thought right. It wasn't enough because we have 128 different characters, but in other languages like Arabic and Russian, you have a lot more to cater for. It's time for you to get into your first task. In this particular task, you will have to name the symbols you see. Pause the video, get your pen and paper, and you can actually have a look and name symbols. Well done for trying. So what do we call this symbols and how many are there? It's time for you to have a go at your first task. Well done for trying. So what do we call these symbols then? We call this symbols letters. And you did rightly know that we have 26 of these letters in the sequence of symbols. So the sequences or any sequence of symbols, we pick from this group of 26 letters, can form words. Now have a look at this, have a go at task two. Now we're going to determine the length of the word, cat. And I'd like you to give another example of a three letter word. Again, pause the video and I'll see you when you've completed the task, Again, well done. Right, the length of the word we knew, or you know, is three letters. And you could have given any example of a three letter word, but I've got three there. We've got dog, we've got hen, we got pet, but you could have given any word. Now consider these set of symbols you see before you. What are these symbols called? And how many symbols can you see on screen? Pause again and I'll see you when you've completed the task. Now, let's look. Symbols we know are called digits and there are 10 of them. And we have a sequence of digits form numbers just like a sequence of letters can form words. So here is task four for you. This one's a counting one. So you've got counting task there. So what is the length of the number 314? So count the digits in the number 314. Also give an example of a digit, a 3-digit number. And also I would like you to think carefully, how many 3-digit numbers can there possibly be? It's time to pause the video and when you've completed the task, we can continue. Well done for trying. So, you know, the length of a number, like rightly counted it are 3-digits. So you have a 3-digit number, which is 314. You would have given another example. It could be any example. There are lots of examples to choose from such as 123, 890, 007, and it's endless. Well, not endless, but the list is quite long. Right. So how many, 3-digit numbers can there possibly be? So you would have articulated and you'd have rightly spotted that you have numbers you can start from sequence 000, and go all the way down to 999. So which means, you've got a thousand possible digits. So if you think you've got nine digits, zero, one, two, three to nine, and there are 10 digits, you will also, as we're working in multiples of 10, if you have 000, all the way to 999, you'd have a thousand digits. But here's how to calculate it. This is more straightforward and easy way. So we're working in base 10 because in our decimal system, we've got 10 digits, 0-9, which we just see. Because we're working in base 10, hence we've got 10. Now it's 10 to the cubed because we've got three digits to consider. So 10 to the cube gives us 1000. And that's how you get that. In your last task, you did some counting and you counted digits, in a familiar number system, which is a decimal system, which we're used to see. So now we're going to go more into binary digits. You're going to learn some more about binary digits. Firstly, what do we call the symbols, 0s and 1s. Now, you know they're binary digits, but they'd been shortened to mean bits. And just like decimal numbers, where we've got digits 0-9, and we've got a sequence of symbols in our letters A-Z, and our binary digits, there are only two symbols. So binary digits are symbols that digital devices, like your computer, use to do their writing. Counting in bits. We've counted in decimal, so we're going to counting bits, binary digits. In this example, we've got the binary digit, 101. Just like we counted the length of 314, the length of the binary number we see on screen is three bits. So you know that 101, when you count the binary digits, you've got three bits. Three binary digits. And examples of three binary digits are; 111, 110, and 000. And you can keep counting. Those are just three examples. So how many 3-bit numbers can there possibly be? So we counted 314, how many 3-digit numbers we saw earlier, can there possibly be? We have the formula we use because we worked in base 10, decimal. But now we're working in base 2, because there can only be two possible digits. So we have to use the number two. Because we want a 3-bit number, a 3-bit number, we're going to have 2 raised to power 3. Just like we had 10 raised to power 3. So in that case, we're going to have 2 x 2 x 2. So you've only got eight possible 3-bit numbers or 3-bit sequences. You are now going to see how Twitter encodes it's characters. So Twitter is a social networking service that sits on digital devices. So we're counting in bits. Now Twitter uses it's encoded characters into 8-bit sequences. So not 7-bits like we saw in ASCII. On screen before you, it's a first message that was sent in 2006, on Twitter. And it says, "Just setting up my Twitter." So we're going to see how many binary digits it takes to represent this message. So let's have a look. Right. So if an 8-bit sequence, which means J when you type J, that gets encoded into an 8-bit number. So same as U-S-T-S and all of the characters will be encoded into 8-bit numbers. So how many binary digit does it take to represent this message? So counting, counting all of that message are 24 characters. So 24 characters each 8-bit, all you need to do is do 24 x 8 and that gives, 192 bits. And that's how Twitter encodes these characters. Now it's time for you to count the bits. In this task, you need to count how many binary digits it takes to represent the message, "See you tonight." Don't forget Twitter uses 8-bit coding scheme, but we're going to go back to ASCII now because that's what our computers, that's the standard that computers are used to. And ASCII is a 7-bit code or 7-bit coding scheme. So pause the video, and when you've completed, I'll see you and we can continue. Right. Well done. So how many binary digits for see you tonight? Right. The final or the total number of digits will be 112. And how did you get that? We know they're 7 binary digits required for each letter. And when you counted, you counted 16 characters, including spaces, don't forget spaces. So 7 x 16 gives you 112 bits. Right, more counting to be done. There is further counting you need to do. So here is this next task. You need to work out the maximum characters in a single text message. And the text message is restricted to 1,120 bits. So how many, 7-bit sequences can fit into this 1000, if I can get this right, 1,120 bits. Remember, we're working in ASCII. Pause the video, and when you've completed your task, I'll see you. Right, great work. So the maximum number of characters in this message, can only be 160 characters. And how do you find that? So you need to find how many 7-bits sequences can fit into 1,120. And all you need do is divide 1,120 by 7, and that gives you your maximum of 160 characters all together allowable in a single text. Now onto some exploration and counting sequences. So let's explore what happens when we create longer and longer sequences of binary digits. We're just going to start with 1-bit. So how many 1-bit sequences can there possibly be? So we're working in binary. So we're working with 1s and 0s, but we want just to 1-bit sequence. So there can only be a 0 or 1. So you can make two unique digits, or two unique numbers, 0 and 1. Right. So you've got there, 2-bits. So what if we increased that to 2-bits? How many 2-bits sequences can there be? So in a 2-bit sequence, you can have a 00, you can have a 01, or 10 or a 11. So that takes it to 4 twice the number of a 1-bit sequence. Now let's take that up one notch. So how many 3-bit sequences can there possibly be? I know you're saying to yourself, I know this I've seen this, yes, I know the answer. That's correct. You're absolutely right. There are eight. And you've seen this before, twice the number of 2-bit sequences. So you can start from 000, to 001, and all the way to 111. So what's the pattern then. So with every additional bit, the number of the possible bits sequence doubles. Now on to our next expiration. In this example, you see a telegraphy system here. We've seen an example of a representation called ITA2, in an earlier lesson. So in telegraphy, each character was encoded using a sequence of 5 bits. So how many 5-bits sequences can there possibly be? And is that sufficient to encode letters, digits and symbols. So bear in mind, we've got 26 letters, 10 digits, and we've got quite a few symbols. In telegraphy, you have seen that each character was encoded using a sequence of 5 bits. So we're working in binary, binary digits. So we're going to go with 2 'cause only two possible digits. So we're going to have 2 as our base number. So we're going to have 2 raised to power 5. We know we're considering 5 bits or a 5-bits sequence. So it's 2 to 5. And if we do 2 x 2 x 2 x 2 x 2, that gives us 32. So if that's sufficient then, I think, you know, the answer is no, because there are 26 letters in the alphabet. And if you consider capital letters, lowercase letters, 10 digits, and over 20 symbols, that's not sufficient whatsoever, to encode the characters on our keyboard. It's your turn again. This time, you'll be counting a 7-bit sequence. This is what you've got to do. How many different characters can be encoded using 7 bits? The hint you've got there is, how many possible 7-bit sequences can there be? Pause the video and I'll see you when you've completed this task. Well done for having a go. Right. We know that ASCII uses sequences of 7 bits to represent characters. So how many different characters can be encoded using 7 bits? Let's find out. We know we're working with base 2. There can only be two possible answers or digits rather. So we've got two digits. Our base number is 2. We've got a 7-bit sequence of 7-bit number. So we're going to have to do 2 to the power 7, which gives you 128, when you work that out. So if this enough to encode letters, digits, and symbols? Let's find out again. We've got uppercase and lowercase letters and we've got 26 of each. That gives us 52 letters all together to cater for. Digits, we've got 10 digits. And there are about 20 common symbols that we need to cater for. So if you add those up, yes, is the answer. 120 characters are sufficient for letters, digits, and symbols. Here's some more counting practise for you. Counting an 8-bit sequence this time. How many different characters can be encoded using 8 bits? And why do you think it was necessary to extend the 7-bit code or ASCII code by 1 bit? Have a good go, pause the video and I'll see you when you've completed. Right. Let's have a look at this now. What's the solution? But before that, here's a small fact for you. Many 8-bit coding schemes are based on 7-bit ASCII. Now onto the solution. You know that with an 8-bit coding scheme, there can be 256 different characters. And how did we get that? You would have worked out that using an additional bit, doubles the number of possible characters there could possibly be. So 128 possible characters for a 7-bit code x 2, gives you 256 different characters. So then why do you think it was necessary to extend the original 7-bit code with an additional binary digit to virtually double the number of different possible characters? The additional 120 characters can be used for representing the characters of a second language alongside English language. A second language like Arabic, Russian, or perhaps Chinese. So that gives so much more option or options rather. Why binary? Why 0 and 1? We could have picked any other pair of symbols. Why those two? Why not 10 numbers and the 26 letters like we're used to using? You do know that binary has two possible states, 0 and 1, off and on. So building binary systems is simpler and convenient for the computer. You can build a binary system using circuits of interconnected switches. Electronic devices are built using these circles of interconnected switches that control the flow of electricity. Switches take many forms, and you're going to look at a couple. The fast one, you can see a vacuum tubes. Now vacuum tubes are made of glass with all of its air removed to create a vacuum. And vacuum tubes control the flow of electricity. And these were used at switches in very, very early computers built many, many years ago. This has now been replaced by the modern transistors, which are much smaller. They also control the amount of electric current and by controlling the amount of electric current, builds on the binary state of 0 and 1. Electronic devices that use switches to control the flow of electricity are now made out of Silicon. And these transistors can be tightly packed into billions and billions and billions or billions and billions of them can be tightly packed into a chip, like we can see on screen. Now looking closely, this Silicon based switches are packed, you probably cannot see what the billions and billions of transistors there're not very visible to the naked eye. So they're quite built in and you're not meant to see. Quite built into some very intricate patterns. And they're very small and quite minute, and kind of atomic, in a way, the size of an atom. So your eyes are not meant to see them. These are the intricate patterns that you can find in your computer. So these goes to explain what happens inside your computer, when you've got your processes, your main memory, your storage, and all your electronic components. You have reached the end of this lesson. So well done. In this lesson, you examine binary digits to a great detail. You know now, that 0s and 1s, are called binary digits or bits. All characters are represented using sequences of symbols. And you did see that binary digits are like letters. They're the symbols that computers write with, like we write with alphabets or our letters A-Z, and numbers 0-1. You also know that computers use two symbols because they're built out of switches. Computers have switches called transistors, which control the flow of electricity. And we saw what switches were used also in very old computers. So well done. It would be nice to see some of the lovely work you have putting this lesson. If you would like to share your work, please ask your parent or carer to share on Instagram, Facebook, or on Twitter @OakNational and #learnwithOak. Hope to see you next lesson.

In this lesson, we will build upon using a decimal numbering system, in order to draw analogies with how numbers can be represented using binary. We will convert between binary and decimal.

Numbers in Binary

﻿Hi there, I'm Sara. I'm your computing teacher for this unit, Representations. And this is lesson four of six, where you'll been looking at numbers in binary. You will need a pen and you will need paper also. Pause the video, and get yourself ready, get a pen and paper. Also, remember to turn off any notifications and remove distractions so you can begin. I'll see you when you're ready. In this lesson, you will explore how a sequence of binary digits can represent numbers, and convert between decimal, and binary numbers. You've just arrived in Binary Land, and you'll be needing to spend your boins so let's look at what that means. So to spend your boins you've got this strange coins we're not going to call them coins, we're going to call them boins 'cause you're in Binary Land. You only have one of each. You can only spend up to a maximum of 31 boins. So, is there any amount that you won't be able to pay with these? Have a think for a moment, pause the video, unpause when you're ready to continue. Yes quite rightly so, the answer is no, you can make up, up to 31 by including and excluding any boin. So let's take a look. Say you needed to spend 13 boins, what boins would you need? You would need eight, four, and one. When you add up eight, plus four, plus one, that makes up the 13 boins that you need. Let's look at another example, you have got 16 boins, eight boins, and two boins. Adding those altogether, makes it 26 boins that you need altogether, for this transaction. In this section, you will see more closely, how a sequence of digital digits are interpreted as numbers. You've seen these before, these symbols, they're called digits, there are 10 of them, and a sequence of these digits, make a number, such as nine, one, six. Let's take a closer look. You've got before you a sequence of decimal digits, four and two. And here are its place values or weights or multipliers. So you've got one place value and tens place value. How do you find out the number? You add the sum of the product, of the numbers, and that gives you the total number. So you've got two, in the ones place value, so that two lots of ones. So two times one, is two. And you've got the tens place value. You've got four lots of 10, so four times 10, is 40, 40 add two is 42. When you see this number, you automatic call out 42 without thinking because you're used to it. So this is how you interpret numbers or a sequence of decimal digits, as numbers rather. Now let's take a look at another example. You've got before you a sequence of three, one, four digits. And what does that mean? It means you've got four in the ones place value, one in the 10th place value, and three in the hundreds place value. So how'd you find out the number? Four times one is four, one times 10 is 10, 'cause you know, one lot of 10, and they're three parts or three hundreds, so three times hundred gives you three hundreds. So when you add 300 plus 10 and four, you get 314. Taking a look at another one. You've got that number, which automatically will call out as 2,718. So starting again you can see, you've added another place value. So can you see a pattern there? Yes, there's a pattern in the multipliers. So you multiply in powers of 10. So why 10 digits? The common belief is, we're kind of used to 10 or we chose a 10 digit or the base-10 number system because we've got 10 fingers. So digitus in Latin, is for fingers. So, we commonly believe that we use the base-10 because it's more convenient for us, to use or count in base-10. In this section, you'll be translating binary numbers to the familiar decimal numbers that you're well used to. You've seen this one before, so have a pause to think, do not pause the video. What do we call these symbols? And how many are there? That's correct. We call the symbols binary digits, bits, and there are two of them. And a sequence of binary digits make a number, like we saw in decimal. So binary is base-2. We've got the picture there of Leibniz. And why have we got him there? He was a, notable figure, who wrote a lot about binary system. He quite a bit about the binary system in early life, and he revisited the base-2 system and did a lot more writing in his career, over and over again. According to Wikipedia actually, he's the first computer scientist and information theorist, but he did not invent binary, and he was well known for his work with mechanical calculators, such as the step reckoner. So that's just more information about Leibniz. So, going on it's the same reasoning you have in binary as you have in the decimal system. So here, we know that there are two digits in the binary system, zero and one. They're called binary digits and that has been shortened to bits. Also, you saw earlier, in a one bit sequence, there are two possible numbers. You also saw that in a two-bit sequence, there are four possible combination of numbers, and in a three bit sequence, you've got eight and each time you add a bit sequence the number doubles. In binary, there are also multipliers or place value. Can you remember, what this multiplier or place value is in base-10, in decimal? Yes, that's right, in powers of 10, 10. So in binary then, can you guess or can you say, what the multiplier will be, in base-2? That's correct again, powers of two. So each one is twice as much as the previous one. Now let's look at an example. So the multipliers are in powers of two, so the place value starting from the right hand side always, you start with one, and that doubles to two, and that doubles to four, and that doubles to eight and so on. So for the digit sequence, one zero zero one, you would have to multiply the multiplier, by the digit, and that gives you the sum. So one times one is one. There's nothing in the second and the fourth place value, so we're not going to do that, it remains zero, and then eight times one is eight. So the sum of the products, added up, would make nine in total. So the decimal value for that binary number is nine. So here is a summary of what we've just done. Have a look for a moment, and just gather what you've just learnt. So we saw earlier that in binary, we use two digits. And that's very convenient for switches, because computers use switches to control the flow of electricity. And that's why we use binary, to form the binary state zero, one, high or low voltage. In a way you can compare binary digits to lamps. When on, it's one, and when switched off is zero. When switched on, you include the multiplier, in the sum. So like the example we've got, eight and one switched on, both multipliers are included in the sum, you count that place value and that equals nine, for that particular number you can see on screen. Right, let's look at another example. You've got binary digit one zero one zero one. You always start with writing the multipliers and you start with one from the right hand side and you go on writing so it's one, two, four, eight. So what will the next multiplier be? Have a pause to think. That's correct, 16. So the multiplier is twice as big as the previous one. In this particular example, can you see the decimal number? By all means pause the video and you can use your paper to work out this one. That's correct. Again, where you see one, include the multiplier in the sum, so for this particular number, or series of digits, you've got 16 and four and one. So 16, add four, add one, makes 21 in decimal. And that's how you do it. Again, bits are like switches. So where you've got the switch of the lamp turned on, you include that multiplier in the sum. So you add the numbers together, and that gives you 21. Right, task one, time for some practise. Convert the binary number you see to decimal. Pause the video and when you've completed, continue. Right, well done. Let's go for the solution. So the first thing you do, is write down the multipliers from the right hand side starting from one and doubling as you go along, so you know what the multipliers correspond to. That's the first thing you do. Then look at all the bits set to one. For all the bits set to one, you will circle them, and write the multipliers in the circle. So that way they're selected. The next step, is to add up, all the multipliers you've selected to get your final number. In this case, you add 16 to eight to two and you get 26. Right, this is like turning on the lamps 16, eight, and two multipliers. So this is the lamp analogy where you've got the switches turned on. And remember the boins? Yes, we've got the boins too. And for another practise so you've got task two here, so convert the binary number to decimal again. Pause the video and I'll see you when you've completed the task. Right, well done for trying. Again, write the multipliers over the decimal number so you know what you're working with. So you start from one and you add you double each time as you go along so it's one, two, four, eight, and 16 and so on, and then the next step, you guess, that's correct. Yes, so you circle, or write the multipliers underneath the digits with one. So in this case you've got 16 and two, and what you do? Yes, you add them up, to get your final number in decimal. This time you're going to learn another skill, converting decimal to binary digits. So you're going to see how this is done. It's exactly the opposite of what you've just seen, so the same principle applies, watch and see how to do this. So, you're going to start with the decimal number 13, you're going to firstly before you begin, you write your multipliers or place value. So you're going to start from the right most section you're going to write one. In this example we've got one, two, four, eight, and 16. We stopped at 16 because 16 is a multiplier that's just above the number one to convert, which is 13. But when you're beginning to do your conversion, take a note, where actually you're going to be starting from the left hand side, the leftmost figure, which is 16. So looking at 16, we're going to check now, what we're doing. Now 16's quite big so 16's bigger than 13 so we're not going to work with that multiplier we're going to set that to zero, we're going to move on to the next one. Right, what have we got there? We've got eight, right, yes eight goes into 13 quite nicely so we're going to set that to one, and then we're going to take eight away from 13 to give us five. So 13 minus eight is five. Now moving on to the next one, what do you think is going to happen? So, four goes into five nicely. Are we going to use that? Set that to one? Will you set that to one? Yes, that will be set to one. So four goes into five, five minus four is one. So, you've got one to make up, now you've got the next column there so do we set this to one? Would you set this to one? Correct, the answer's no, because two's too big to go, two's too big for one so we're not going to set that to one so we're going to use the other multiplier the other place value column, because one fits in nicely, and then we can just set that to one and the answer's yes there. Okay. So, just take a moment to have a look before we go into the next screen. Right, perfect. So when you add up, just to check that you've got the correct answer. You add up eight plus four plus one, it gives you 13. Right, let's try another example. Have a look at this. We've got 22, again we write, first thing you write your multipliers starting from one so we've got the number 22 to consider, 16 goes nicely into 22 so you know, you're going to set that to one. So the next thing you do is 22 minus 16, and that gives you six. So you've got six, right, let's go on to the next, column there, and eight is too big for six so, you're going to set that to zero. So moving on to four, what would you set that to? Would you set that to one? Yes. Because four goes nicely into six, and you get a remainder so six takeaway four gives you two so you've got that to make up. We go on to that column then what do we do? Do we set that column to one? Fantastic, and that's a yes. So two minus two is zero so there's no more digits to consider and that gets set to zero. Right. So adding up all your multipliers where you've got one, gives you 22 in decimal, with 16 adding four, adding two being 22. Right, so now you've seen how to do the reverse it's time to practise that skill. Look at your task three, pause the video and when you've completed that task, you can unpause and we'll look at the solution together. Right, well done for having a good go. So the first thing you would do, would be to write down your place value or your multiplier so we've started, with one from the right hand side all the way to 16. So remember we're converting 16 to binary. So what we did is consider, the number 16 and that fits nicely in the first right most place value or multiplier, so that gets set to one and every other digit you replace that with a zero as a place holder that gives you your solution. So note that down. Fantastic. That's just telling you how to get through that. Right, okay. So on to task four. Pause the video and have another go, this time you've got 19 to convert to binary. So decimal number 19 to convert to binary, pause the video and I'll see you when you get back. Again, check your answer. Well done. And that should give you 19 in decimal. If you're unsure any time just pause the video, go back and just check with your notes and then you should be able to work out how that's done in the correct way. So well done. Now this is a very interesting one to do, so you will enjoy this one. So remember you're in Binary Land, you're in Binary World so your friend, the friend you've just made in Binary World has a birthday. So your friend's birthday in binary is one one zero zero one, and one one zero zero. So that's what your friend has written on a piece of paper to you about their birthday. So can you work out their birthday in decimal, look through the worksheet, complete your task and when the task completed, continue the lesson. Right, well done for trying. Yes, this is a very interesting one. So the first set of digits you saw, converts to 25. So this must be the day, and the next set of digits you saw, converted there nicely to 12. So what do we have there? It looks like your friend's birthday it's on Christmas Day, 25 of December. So, her birthday's on Christmas Day. Now the next one, how old is your friend? And the clue was in the candles. So remember the lamp analogy where we had the lamps on, ones and zeros, ons and off. So the first candle there's on, you've got the next two candles off, the next one's on and then the next one's off. So that would give you in binary one zero zero one zero. And when you convert that using all the skill you've learned, that's 18. So your friend's 18. So well done. In this lesson you've acquired some really useful skills in binary, that would stand you in great stead in Binary World so you'll be at home with your friends in Binary Land. So in this lesson, what have you learned? You have explored how numbers can be represented as sequences of decimal numbers, and binary digits. You have also been able to convert between decimal and binary, and vice versa binary to decimal. So in the next lesson, you're going to see how to count really, really, really long binary numbers. So I hope you're looking forward to that as much as I am. Right, before you go I'm going to leave you with a puzzle, and a joke. So see if you get them. Yes you're right, it's certainly not 10 so it's not for the bigger girl, it's one zero, and if you write your multiplier or your place value starting from the right most hand digit you have one and two, so that gives you two. So that cake belongs to the two year old because we're in Binary Land. So, well done for spotting that. So the last one is a joke. So there are one zero kinds of people in this world, those who understand binary and those who don't. Have a pause to think. Right, again I'm glad you did understand that because there are only two kinds of people in binary. So well done, hope to see you next lesson. But you've had such, you've acquired such good skills and it will be really nice to see what you've done for this lesson. So if you'd like to share your work, please do ask your carer or your parent to share your work on Instagram, Facebook, or Twitter @OakNational with #learnwithOak. Hope to see you next lesson.

In this lesson, we will explore the prefixes used for measuring size, such as 'kilo-', 'mega-', 'giga-', and 'tera-'. We will revisit digital computing devices using binary digits to represent all information (including programs).

Large Quantities

﻿Hi there, I'm Sara I'm your computing teacher for this unit representations. This is lesson five of six, large quantities. You will need a pen and you'll also need paper. So pause the video, get pen and paper. And when you finished unpause, but before that, don't forget to remove all notifications also and any other distractions, see you when you're ready. In this lesson, you will understand the meaning of bytes. Learn what the prefix is kilo-, mega-, giga-, and tera- mean practise converting between units. In this lesson, you will understand the meaning of bytes. Learn what the prefix is, kilo- mega- giga- and tera- mean and practise converting between units. So here's a question for you, why measure? We use nanometers to measure the size of molecules, centimetres to size of objects and kilometres the distances between cities or towns. Why then do we use different units of measurements? Think about that. Pause the video and continue when you've had a good thought. Why measure? Measurements required tools and provide scientists with a quantity. A quantity tells a scientist how much of something there is and how many there are. Scientists on the other hand use units to describe how something is measured and use different units to measure different things. For instance, kilogramme for mass, seconds for time and so on. A common measurement system allows us to make direct comparisons, for instance, no good saying 10 eggs weighs as much two apples. What does that mean? Using different units and prefixes, however is not specific to computing, but common to all scientific practise. Now, in this lesson, you will see how units for measuring the size of binary representations are used. Time to explore units of measurement in computing bits and bytes. And computing, it's quite common to group binary digits into chunks of eight. A group of eight binary digit is called a byte, but you've got to be really careful because a bit it's one binary digit, which can be a zero or one and a bit it's is a smallest unit of in computing. A byte however, is a group of eight bits and a byte is denoted using uppercase B and a bit lower case or bits lower case b. So here are eight binary digits. So what's that called? You've just seen in blue there, the definition, a definition, so what's that called? Do you think, what would that be? That's correct, this is one byte. Now, since you're getting really good at this, here are 24 binary digits. Now remember a group of eight binary digits it's called a byte. So what would that be? How many bytes? That's correct, again, three bytes, because you can get three, lots of eight. So all you do is divide 24 by eight and you get three bytes. So remember bytes, is denoted using capital letters B and bits denoted using small upper case, lower case, rather b, right. Now here before you are 128 bits all together, what is the size in bytes? So going back to the very last example you saw what you think the size in bytes is? Again, well done, correct. So it just means how many groups of eight can you form with 128 bits? And when you divide 128 by eight, you get 16 bytes. So it's 16 uppercase case B denoting bytes, So converting bits to bytes, here is a visual aid to help you remember what to do. So you're converting bits to bytes so going from a smaller size unit, so to speak to a larger size unit. And what you normally do is divide by eight because this is how many groups of eight bits would fit into that sequence, whatever sequence or number of bits given. So converting bits to bytes. Now here's another one for you. So now, you're looking at this, from the other perspective, you have a piece of text 16 bytes long. So you know that there are 16 groups of eight bits. What is the size in bit? Again correct, so you've got the 16 groups now going, doing the opposite of what you've just done. So you will multiply 16 by eight, and that will give you 128 bits. And remember the bits is in lower case. So bits lowercase b. Right, again, using this visual aid to help you when converting from bytes to bits. So you're going, if we could use that expression from a bigger sized unit to smaller sized units, you will be more supplying by eight. So going the other way from bytes to bits, you will multiply by eight. So again, just a reminder before you go onto your worksheet to get some vital practise, here is a visual aid to help you. So from bits to bytes, you divide it by eight and from bytes to bits, you multiply by eight and don't forget a bit it's just one binary digit, and it's the smallest unit in computing and a byte on the other hand, it's a group of eight bits. So pause the video and access your task one, you can either write on your worksheet or you can use your paper to work this out when you have finished and completed this task, just play to continue, right? Well done, well done for having a go. So in the question you were given, you had a simple file called simple, and it's the size of the file is 12 bytes is a text file. And the question asked you how many binary digits or bit does the file contain? So using your conversion diagram, that help you, you're converting from bytes to bits from the bigger units, a smaller unit. So you'd have to multiply, remember bytes group of eight. So you multiply by eight to get 96, and that's your answer. Time for some more practise. In this task, you need to complete the last column on the given table. You need to find out how many bytes required for each character or symbol that has been provided on that table. So have a go. And when you've completed, just play to continue. Right, well done. So you've got here character symbols. You've got that at sign. You've got the pound sign and the binary representation is given on the next or second column. So the first example, you've got eight bits and you've actually been given the number of bits. It's been counted for you. So don't forget using your conversion diagram. You need a number of bytes. So you're going from bits to bytes. And when you're going from bits to bytes, you need to divide. So in the first example, we'll divide eight by eight to get one byte, and you do the same for all the other symbols to get your answer. So check your answer and continue pause for a bit to check your answer. You can continue once you're done that. In summary, then every piece of data found on the computer is represented as a series of binary digits. Zeroes and ones bits. So it doesn't matter whether or not it's a text file or an image file, or sound file, an animation. Everything stored are sequences of bits. Computing devices have the capacity to store enormous amount of data. So sequences of binary digits health can soon get really long. Take a look of what we mean by that. The chapter in a book for instance, can hold a few thousand bits, a song or photograph, a few million bits, a film can be a few billion and say all the files on a computer, all the files in Wikimedia for instance can take or hold of a few trillion, or how do we describe these long sequences of data? Now here before you Pico and Giga are having a conversation. And Giga is saying to Pico up my favourite song is 24,354,768 bits, that's a mouthful. We don't normally talking that much detail. What we would normally do is talk or use multiple to describe what we mean like millions. So the prefixes using computing, you saw earlier that scientists do use prefixes to denote multiples of units. The prefixes used are kilo- for thousands, mega- for millions giga- billions and tera- trillions, and the short form notation used are K, M, G and T. For example, 3000 grammes is three kilogrammes or three kg. Right, so let's look how prefixes can be used with bytes and bits. So Giga is saying to Pico here. My favourite song is 24 million bits. Phew, so that's replace that long number we saw earlier. So it's common practise to to actually speak this way, but instead we can use multiples such as mega to replace millions to say, or describe what we mean. So Pico can say for instance, 24 megabits instead, now that can be further shortened by use of the short form M and lowercase b for bits. So it can become 24Mb that's even shorter. To convert the, the bits to bytes, just replace the lower case b with uppercase B. And that will be three megabyte and Pico is rather impressed by that, right? So the size of a sequence, which is 24 million binary digits long can be described as three MB. Can you see why? That's correct. So that's bits, binary digits, and what's been described here is in bytes. So what's happened is bits converted to bytes, make three, you know there are eight groups of eight bits in a byte. So to go from a smaller size unit to your larger size unit, you will be dividing. So 24 divided by eight is three, and the million is mega. And the short form is M and B for bytes, because it has just been converted. To really understand how to describe sizes, let's try the other way too, right? Pico this time is saying my operating system is two GB. Now you can expand GB for short form and use prefixes. The prefixes you saw earlier, you will remember that G stands for giga and B stands for bytes. So easily Pico could have said two gigabytes. Now what comes next? Yes, you can also expand even further by using multiples. You saw how we use multiples to describe sizes. So instead of gigabytes, Pico can say my operating system is two billion bytes and also Pico can convert byte to bit. And all Pico needs to do is just convert it, and it becomes 16 billion bits. Now you remember that eight bits make a byte. So all Pico going back again, all Pico had to do was just multiply two by eight. And that converts bytes to bits and Pico can say my operating system is 16 billion bits, and that really impressed Giga. Cause you could see the expression on Giga face, like wow. So Pico can now say that his operating system or her operating system is 16 billion binary digits. So that's how you can describe sizes, really, really long sequences of bits. Now it's time for you to have a go at more practise so you can find your way around units and prefixes. But before you do that, you have been provided with a help sheet. This sheet summarises all the definitions and helps you find your way around conversions. So you can easily carry out the conversions with the visual aid provided. In task three, you will be comparing between sizes to start with all you need doing this task is order the sizes you've been given from smallest to largest in ascending order. And by all means pause the video. And when you have completed the task, just play to continue. So here's the answer. The smallest size would be 23 kilobytes ranging all the way up to two gigabytes. So take a look and check your answer. More practise, this will help refine all you've learned and the skills you've learned. In this particular task, task four, read the question in the worksheet and complete pause the video by all means. And when you've completed this task unpause to continue well done, so let's go through the solution together. So how many bytes is one terabyte? So to get the answer, you've got to work logically. So you know the number of bytes in one terabytes, so tera- you need to kind of describe or expand it. So you're going to expand that notation. What does tera- mean? Tera- means trillion. So you're not using the prefixes. You're interpreting the prefects. So all you need to do is replace tera- with trillion we want trillion bytes. So one terabyte is one trillion bytes. So the next tech now is how many bits is one terabyte. So you've got bits and you've got bytes. So that's the first hint. So the number of bits in one terabyte, how did we get eight million bits? We're working from a smaller unit to a large sized unit. So you're converting from bits to bytes and you know, there are eight bits that make a byte. So all you need to do is one times eight will be eight and you replace your bytes with bits, you've just converted it. So it'll be eight trillion bits will be your answer. So some more practise really embed that knowledge and the skill you've just learned. So have a go at this one, how many will fit? Read the question in the worksheet and complete. You can also use your notepad and if you're not using your worksheet, so that's fine also. Don't forget to use a cheat sheet, to look at the definitions and see how to make the conversions using the diagrams given on the cheat sheet. So pause the video and when you've completed this task, just unpause to continue. Well done for having a good go. So let's go through this one. You really enjoy taking pictures with your mobile phone. So you purchase a 16 gigabyte memory card, and you want to know how many pictures you can store on your memory card. So the average size of a picture is approximately four megabytes. So the first thing you notice here is that you've got a mismatch of units. So you've got to convert to make sure the units match. You've got 16 gigabytes and you've got four megabytes. So you need to convert first because you know, 1000 megabytes make one gigabyte. You will multiply 16 by thousand to convert your gigabytes to megabytes. So you've got 16,000 megabytes capacity on your memory card. So the next step will be now to find out how many of those four megabyte pictures will fit in your memory card. That's just going to be a simple case of dividing by four, because you want to know how many four bits fit in. And when you do that calculation, you arrive at 4,000. So 4,000 pictures will fit Well done, you've come to the end of this lesson and you have gained really vital skills. And you now know how to describe really long sequences of bits. Now you have seen that all pieces of information I've represented as sequences of binary digits or bits. So it doesn't matter whether it's a sound or text or animation images. Everything is represented as sequences of bits and you know that to handle or describe this very long sequences of bit, prefixes can be used when we describe these sizes. If you would like to share your work with Oak National, please do ask your parent or carer to do so on Instagram, Facebook or Twitter @OakNational, with the #LearnwithOak. Hope to see you next lesson.

In this lesson, we will complete a set of tasks followed by a puzzle activity that utilises conversion between binary and decimal.

Turing's mug

﻿Hi there, I'm Sara, your computing teacher. This is lesson six, and the last lesson on the unit, "Representations from K to Silicon". In this lesson, you will need to take down some notes. So get yourself a pen and paper, pause the video, and when you're ready, unpause and continue. Don't forget also, you need to turn off all notifications, so they're not distracting, and remove any other distractions before you begin. So see you when you're ready. In this lesson, you will convert binary digits to decimal digits. You will convert decimal digits to binary digits also. And you will find a secret code. You have learned some really vital skills. So why not brush up on some of the skills you've learned? You can do that by having a go at binary digits in your task one. Complete the questions on the worksheet. Pause the video, and when you have completed, just unpause to continue. Well done for having a go. Now, check your answers for questions one to four. Now on to task two. Again, complete the questions on the worksheet. Pause the video, and when you have completed, just unpause to continue. Well done for having a go. Now, check your answers against what you've just done. Now, onto the last task before we begin the lesson, right? Pause the video and complete the task where you've been required to fill in the gaps. When you have completed, just Play to continue. Great work. I bet you're wondering what we mean by Turing's Mug, so I won't keep you so you can find out. Alan Turing was an English mathematician and a very good one at that. He's widely considered to be the father of computing and during World War II, his secret work at Bletchley Park was central to decrypting or breaking German communications, which helped win the war. Now, what do we mean? What's the story behind Turing's Mug? So Turing was an eccentric man. In his wartime office he would lock his mug to the radiator with a combination lock, so no one could use it. Now you have been commissioned with this very special mission. The national museum of computing has uncovered a clue that may help unlock the Mug. They have asked for your help. They let you into Turing's office and show you the clue. Now, before we begin, I will show you an example of the clue that was uncovered. So this is a series of representation ahead that you can see on screen, and you've worked out that these refer to binary numbers, So I've put there the place value or multiplier, so that would help us as we go through this example. So take a first look. Now taking a closer look, you will remember that you do start from the rightmost place value, which is one. Now, you looked carefully and you've rightly worked out that the white circles are zeros and the black circles are ones, 'cause they've been turned on. So starting with the first line, the first actual circle there will be zero. And moving on from there, the next four will be one, zero, zero, and zero. So adding up just the ones, looking at the place value for the digit we're on, you've only got two. So that equates to decimal number two. And as script analyst, you soon worked out that that corresponds to letters in the alphabet and the second letter in the alphabet is B. Right, going on to the next line, the code there would read as binary one, zero, zero, zero, one, zero. And adding up the ones, that would give us a nine, and the ninth letter in the alphabet is an I. So you carry on with deciphering what this means and you get the word Bicycle. So the letters actually form a word. Right, okay. So next, you've flipped through Turing's notebook trying to find clues. And on the last page, you find a list of words, with the word bicycle, which has just been broken, on it. Now this is the list of words you find. Now there's bicycle there, and there are three numbers beside the word bicycle, but what are the three numbers? Right, okay, moving on. Now you also notice the combination lock and this is an example of a lock. So how do you begin to break this? Okay, you've soon worked out that this lock corresponds to binary digits. And in this particular example, you've got the place value four and two set to one. So when you add four and two, you get six. So the decimal value of this binary number is six. Looking at that binary number, you soon worked out that these bars, horizontal bars and vertical bar, switches on, depending on whether you've got a zero or a one. A zero meant it's switched off, and a one means it's switched on. So you trace the first digit, it's a zero. So that's traced all the way along to that horizontal bar. So that's not switched on because that's set to zero. Onto the next number, that's set to one. That combination lock digit is set to one, which means that traced all the way to that vertical bar, means the vertical bar needs to be switched on. So it's switched on. Onto the next number, right? Set to one, and that there means that vertical bar there will have to be set to one also. So that's set to one. No need continuing, because all other digits are set to zero, so that means that corresponds to a one on your combination lock or on the combination lock given to you. So that will be a one. Right, so what are the instructions? Now, you know what to do. For each number, you set the switches according to the binary number. So you checked a digit. If it's set to zero, then that bar remains off. If it's set to one, like that one, it's on. The next one, set to one, that's on. That's set to zero, that's off. That one's set to zero, that's off. That one's set to one, that's on. And that last one's set to one. So that horizontal bar should be on. So that's how you work it out. And in your worksheet, feel free to colour in as you find switched on digits. So what does this mean for Bicycle? Because we found, or you found, three words next to bicycle, 109, seven, and 111, in this example. Right, working out what this means, the first digit here, or the first number here, the binary digits, we're going to try and switch on depending which one's on and off. So in this example, we've got the first ones on, so we'd go right there and we trace all the way to that horizontal bar. So that should be on, that's on. The next one's off, so that's going to stay off. But the next one under the place value force on. So we're going to trace all the way there. So that means that bar needs to switch on, which it does, and the next one's also on, so that bar needs to switch on, which happens. And the next one's off, but the last two are on, so it means that vertical bar there and that horizontal bar there needs to be switched on, which we have here. So that reveals the number five, so we've got the first digit that we could unlock the combination lock with. Now, carrying on with that same, in that same manner would uncover the number seven and the number nine. So which means the pattern to unlock the lock is five, seven and nine. It's your turn now to have a go at unlocking Turing's Mug. So you've got a pattern in your worksheet. Remember what the white stands for and the black. So the black circles mean to switched on, the white means they're switched off. Now you suspected these are binary numbers, so you try to convert them to decimal numbers. So follow what you've just discovered to resolve and unlock Turing's Mug. So have a go, there's a table that would help you. And you've got your list of words and instructions. So have a go at Task Four, at unlocking Turing's Mug. Pause the video, and when you have completed, unpause to continue. Here's the solution. If the word you uncovered, the word you cracked, is Enigma, then well done for deciphering that. And that means you have unlocked Turing's Mug, well done. You have reached the end of learning for this unit, Representations. You have gone right across time, as far back as thousands of years ago, where you saw representations in the form of clay tablets, to modern day times, where you have digital tablets. You saw how humans resolved the problem of storing, transmitting, and processing information by inventing writing. You also saw that just like how humans have the need to write, computers have the need to write also. And computers write using ones and zeros. And all information held on a computer, be they text, images, sounds, whatever they may be, are all in sequences of ones and zeroes, called binary digits. So great learning. On your notebook, I would like you to write one thing that impressed you, one thing that you learned, and one thing that you really did not enjoy, and this is just all to bring this learning together and for you to have a good think about what you've learned in this unit. I hope you enjoyed it and thank you for joining. It will be lovely to see your work. So if you'd like to share, please ask your parent or carer to share on Instagram, Facebook, Twitter, @OakNational with hashtag #LearnWithOak. Thank you for joining. And I hope you really enjoyed learning all about Representations, from clay tablets to modern day digital tablets with silicon chips in them.

Unit Overview: Representations: from clay to silicon

Lessons: