Video: Asking questions

﻿Hello, and welcome to lesson three of the selection in quizzes unit. My name's Josh, I'm your computing teacher. And in this lesson, we're going to look at asking questions, and how questions can affect the flow of our programmes. You are going to be using the Scratch website, so make sure you have access to a web browser. If you're under the age of 13, remember you will need a teacher, parent, or carer to help you set up an account if you would like one. You don't have to have an account, but remember to download your projects after each task or after each lesson to ensure that you have them for future reference. You will also need something to write on and with, so make sure you've got those to hand. If you've got all those bits ready, let's crack on with lesson three. So in lesson three, you're going to be able to explain how selection can direct the flow of a programme. In order to do that, you're going to be able to explain that programme flow can branch according to a condition. You're going to design a flow of a programme using the if, then, else structure. And you're going to show that a condition can direct programme flow in one of two ways. So on the screen you have algorithms in action. You have a question and you have two different outcomes. You've got outcome, if Paris is said. So if the answer is true. And the outcome, if it's not Paris, is given. It's laid out in a very linear fashion and it's quite difficult to understand what would happen if someone was wrong, because you have to skip the correct part first. So what we can look at it like is a branching structure, which is very similar to the branching databases. Now, you've got your question at the top. We have our condition in the centre, so answer is Paris. That's our condition. And then it branches two ways. You got true, so the answer given is Paris, and false, the answer given is not Paris. And you've got your outcome. If it's true, which is say, "Correct!" And you've got your outcome if it's false, which is say, "Wrong answer!" And this is very much the way that the structure works, using the if, then, else block. So you have your condition. If it's false, the outcome is this, if it's true the outcome is this. And it branches off just like that. And it's much easier to see which way you are going to go down that branching root. What we have on the screen now then, is a programme for the question "What is three times four?" Pause the video and see if you can identify the condition, the outcome if it's true, the outcome if it's false, and anything else you can spot in this programme. So hopefully you've had a bit of time then to think about where the condition is, where the outcomes are, and anything else you've managed to spot in our programme. So we have our question, which is "What is 4 x 3?" We have the wait part of that command block as well. Now wait means that we don't need to use an infinite loop because the programme is designed to wait for an answer. So we don't need any repetition in there, because of that wait part of that block. We got our condition, the answer is the same as 12. So answer equals 12. We've got our outcome if the condition is true, which is say "Correct!" And we've got our outcome if the condition is false. And that is using that same branching structure that we looked at on the previous slide. So let's have a quick look at what that will look like. As you can see, we've got our condition, the answer, and we've got equals 12. Okay, so, let's have a look at some user inputs and see where they would fit into our true/false columns. So the first answer, the first user input is 12. And you can see that the answer equals 12, so that would be true. Okay. The next user input is eight. We know that's incorrect, so that would be false. And it would go down that false path. We've got the user input equals 15. Again, that's going to be false, it's not the answer equals 12. We have answer input equals yes. Again, it doesn't equal 12, it's not going to go down that true column because it's false. Okay, and final one, user input equals twelve. Now this one's really important because we all know that that is the written word for the number 12. So technically the answer is right, but the programme doesn't know that, 'cause we've specified that the programme should be looking for 12 the number, and not twelve the word. So although four times three equals twelve, and that's correct, it's still going to go down that false column because the computer programme doesn't know that that is a correct answer. So it all comes down to the answers that we give and the conditions that we say are going to be the correct answer. So it's really important that we have those things in mind when we're moving through our selection in quizzes unit. So we're going to look at what happens if conditions are true or false. So on the screen you've got a programme on the left hand side, and you've got two outcomes, you've got A and B. Pause the video, decide which one is, which one will happen if the condition is true, and make a note of it on some paper or on some notes somewhere. Okay, because you will need that for your first task. So pause the video and have a go at doing that now, resume the video when you're done. Okay, welcome back. As I said, we are going to be using this for our task, so we're not going to go through the answers just yet. Here is another one that I'd like you to write down the answer to. What will happen if the condition is true? Pause the video. Write down A or B. It might be worth writing down exactly what will happen, so that you have that knowledge and not just A or B, because we won't be able to show these slides again. So pause the video, have a go at this one. Okay, as before, we're not going to show the answers just yet, 'cause you are going to be testing these in a while. Final one then. What happens if the condition is false? Pause the video and decide if it's A or B, make a note of the actions, the outcome, and resume the video when you're done. Okay, welcome back. As I mentioned, we're not going through the answers just yet, because your first task is to have a go at running the programmes, running the codes and checking your answers against what will actually happen. Okay, so open up p5b3-1, have a go running those codes, checking what happens to each of them, and see how you've got on with that. Pause the video, resume it when you're done. Okay, hopefully you had a bit of time then to have a go at those codes, run them, see what happens, check the answers that you'd written down and make sure that you had identified correctly what would happen if the conditions were true for the one and two, and what would happen if the condition is false for the third one. So we're going to go through the answers together, and see the outcomes that happen based on the user input. So for the first one, we were looking to find out what would happen if the condition was true. And if we read through the code, we can see that the condition is touching dinosaur four, and if that's true, then we'll say, "Oops" for one second. And that is A, as you can see there. So if the sprite, it's a Scratch sprite, is touching the dinosaur, he's going to say "Oops" for four seconds. That is if the condition was true. The next one then, what happens if the condition is also true, we've got, "What's your favourite number?" And if the answer given is 10, then what's going to happen? Okay? As you can see, if we read through, we've got "Turn clockwise 45 degrees, wait one second and turn counterclockwise 45 degrees." So B is our answer for this one. That's what's going to happen if the answer given to the condition is 10. And the final one then is what will happen if the condition is false? And hopefully you noticed that that's not the same as the previous ones, because it's looking at what will happen if the condition is not true, rather than when it is true. Now our condition was, left arrow key pressed. And if that's not happening because of our forever loop, we are going to be using the else part of our structure. And that is going to be A. Next costume, "Wait one second." Next costume, "Wait one second." And with that forever loop, that will continue to happen until the left arrow key is pressed and it will continue to happen when the left arrow key is released. So that is the outcome that will happen when that condition is false. So hopefully you were able to go through those programmes and you were able to understand what will happen at each junction, each time a condition is either true or false, and you were able to do that within the programme itself. So we are going to look at designing outcomes. On the screen we've got our algorithm that we looked at earlier and the way it is in our branching structure. Now we're going to create something similar to this algorithm. The way you're going to do that is you're going to select a question, that you're going to, your sprite is going to ask your user, and you're going to use an algorithm with a branching structure to identify the condition, the if part of our programme. The outcome if the condition is true, the then part, and the outcome if the condition is false, the else part. So on your worksheet, you're going to have a table which has questions. So you can select a question from the table. And it's got outcomes, so you can select your outcomes from the table as well. So you can select an outcome if it's true, if the condition is true, and an outcome if the condition is false. You've also got your algorithm template, so you've got your branching template to use as well. So if you have printed the resources off, you can use that algorithm template to create your branching structure. But if not, make sure you're drawing it out in the same fashion so that it's easy to see what will happen if your condition is true, and what will happen if your condition is false. So pause the video, have a go at creating your own algorithm. And resume the video when you're done. Okay, welcome back. Hopefully you had a bit of time then to create your own branching algorithm. And you were able to add a condition, add an outcome, sorry, if the condition was true, and add an outcome if the condition was false, and you selected one of those questions from the table. What we're going to do is we're just going to have a quick look at our own algorithms. And I want you just to identify whether or not, pausing the video briefly, whether or not it includes the question that will be asked it includes the condition, the outcome if the condition is true, and the outcome if the condition is false. Okay, just make sure you've got those supported, if you don't, make sure you've got those there, because you're going to need them for the next part. Okay, welcome back. Hopefully you were able to identify those different parts in your own algorithm. If you manage to notice that you've missed something, make sure you are going back and just adding that in now, because we are going to need it when we move on to our next step in this lesson. So the next thing we're going to be doing is we're going to be be implementing our algorithm as a programme. So you're going to be doing this in the Scratch website, and we're going to need to make use of these command blocks. We're going to use the ask something and wait. We're going to need to use the condition equals something, the answer equals something, and we're going to need to use the if, then, else structure. So how will you make use of these blocks when you're implementing your own algorithm? Let's jump into the Scratch programme and just have a quick brief look at how we can create and implement our own algorithms using this selection block. Here we are then in the Scratch programming software, and let's just go through very quickly using some of those blocks to create a selection-based programme, which answers a question, whether it's true or false, with an outcome. So the first thing we're going to need to do is just add an event block, so when the green flag is pressed. We then need to head on into the sensing menu down here, and we need to select our ask "What's your name?" block. And we're just going to delete that question for now. The next thing we're going to need to add is a control block, our if, then, else. Remember we don't need the forever loop because we have our ask and wait. So it's going to wait until the answer is given or the input is given. We then need to find our block for a condition. So we're going to use the operator, I'm going to use this equals here and add that in. And we're going go back to sensing and we're going to find our answer block here. So now, ask something and wait, if the answer given by the input by the user is equal to something, then we can do the next step, so we can look at what our condition, if it's true, what our outcome for that condition will be, and what will happen if it's false. So what will happen if the outcome is false. So we can do that by adding in say blocks. We can also add in turn, we can add in move. You can add in pretty much anything you'd like. What I'm going to do is I'm going to add in a move. And I'm going to say move 50 steps, and just say "Done" for two seconds. If not, my sprite is going to change costumes, costume two. And it's going to turn clockwise 360 degrees. So he'll end up back where he was. So I'm going to put my question as, "Would you like me to move across the screen?" We have to be very careful here what we put in here, because our answer needs to be exactly what the user input will be. So we're going to say yes, and then that is my programme ready to be tested, so I'm going to test my programme now. I'm going to press the red stop button first, press the green button, and you can see that my sprite is asking me, "Would you like me to move cross the screen?" I'm going to say yes. And he moved 50 steps across the screen. So that's one way to implement and create your own programme using your algorithm. So let's go back to the slides and see about your last task for this lesson. The final task then is to implement your algorithm as a programme in the Scratch software. So open up scratch.mit.edu. Create a new programme, and implement your own algorithm into that programme. Okay, so you'll need to make sure you're making use of those blocks that we pointed out previously. And you are creating your own programme with the outcomes that you selected. Run it, test it, make sure it works, and then resume the video when you're done. Okay, welcome back. Hopefully you managed to create your programme, you implemented your programme using the algorithm and the branching structure that we discussed in the earlier part of this lesson. And you were able to make it work the way you wanted it to work. So well done if you did. If you didn't, feel free to explore, pause the video again, go back and explore, figure out how to make it work, and then resume the video when you're done. We've got a final thing to look at before we move on to the end of our lesson. So, pause the video, and I want you to decide which way the inputs will force this programme to go. So will it go down the true route or will it go down the false route? So which outcome will it select based on the user inputs? So, the first user input is 12. Pause the video, have a think, which way is it going to go? Is it going to say "Correct!", or is it going to say "Wrong answer!"? Okay, welcome back. Let's have a look at the next one. Pause the video. The answer given is 11, the input given is 11. Is that going to say "Correct!", or is it going to say "Wrong answer!"? Pause the video and decide. And the final one then is the answer 11 as a word. Pause the video, is it going to say "Correct!" or "Wrong answer!"? Okay, welcome back. So let's go through those together then. So the first answer given is 12. The question is "What is 4 x 3?" Hopefully you know that four times three is 12. And the user has given the input 12. However, if you look at the answer equals part, our condition, the answer equals 11. So although four times 12 is, four times three, sorry, is 12, the answer in our condition is 11. So it's going to say "Wrong answer!" And that's all based on that input given and the answer that's specified by the person who has programmed it. So that's going back to that really important fact that we need to make sure that what we're putting into our condition is correctly spelt, is the correct answer, because then when people run the programme, or run the quiz in our example, they're going to get the wrong answer, even though they've given the correct one. 11 then if the number 11 is put in, and that will give the correct answer. Again, it's not the right answer to the question, but it is the correct condition answer. So again, it's really important that we're making sure that our condition is correct before we share our programme. And final one, as we mentioned earlier, if we're using the word eleven, it's not the same as our condition answer. Our condition is 11, the number. So it's going to give the wrong answer. So it's all about making sure that what we're writing into our condition is correct in order for it to work as we expect it to work for our users. So that is the end of lesson three. And I hope you enjoyed implementing your algorithm as a programme and just working out how to ensure that the true and the false outcomes are correct, and the answer in the condition is correct as well. If you would like to share your work with us, as always, we would love to see it. So consider doing that and ask your parent or carer to share on Instagram, Facebook or Twitter, tagging @OakNational and #LearnwithOak. I'm really looking forward to lesson four, we're going to be moving on to designing our own quizzes. So hopefully you are just as excited about that as I am. And I really look forward to seeing you there.

Worksheet: Asking questions

Exit Quiz: Asking questions

Completed: Asking questions

This lesson, you will consider how the if… then… else… structure can be used to identify two responses to a binary question (yes or no). You will learn how questions can be asked in Scratch and how the answer is used to control the outcomes. You will then design a program that uses selection to direct the flow of the program. 

Computing

Asking questions

Video

Worksheet

Final Quiz

Lesson Complete