The Scratch Calculator You are all going to be real computer programmers!!! www.computerscienceuk.com This Half Term’s Project • Computer Programming – The Scratch Calculator www.computerscienceuk.com Lesson Objectives Learning Objectives • Understand how to create a sprite • Understand how to create a new background • Understand how to move the sprite • • • Understand how to input values into scratch Understand where our inputs are stored Understand how to output values onto the screen Lesson Outcomes • Create a simple program whereby the sprite (which can be moved by the user) asks the user a few questions and responds to the users answers. Literacy – Key Words Sprite An object which can be programmed in scratch Scripts A piece of programming code in scratch Inputs Values which get sent from the user into the computer Variables The place where inputs get stored by the program Outputs The values which get sent from the computer to the user www.computerscienceuk.com Scratch • Scratch is an application which allows you to ‘program’ • It allows you to use and create ‘Sprites’ which are simply characters and objects • It allows you to program these Sprites so that they move and interact with each other and the user. www.computerscienceuk.com Familiarising yourself with ‘Scratch’ Instructions and Controls Scripts Area Sequence of Instructions The Stage Sprites www.computerscienceuk.com Designing a new sprite www.computerscienceuk.com Designing a new background www.computerscienceuk.com How do we program? • Programs are not that different from us. • In fact, programming is all about teaching the computer to think just like us (humans)… www.computerscienceuk.com If a computer is a box… …think of a program as a man inside the box! www.computerscienceuk.com “Tell me what to do and I will do it!!” …and programming is all about instructing the man to do what you want! www.computerscienceuk.com The man in the computer (program) thinks just like a human. If we taught the man how to have a conversation with the computer user, what would be the first thing we would tell him to do? www.computerscienceuk.com Inputs → Storage → Process → Output • Conversations start with a question. • In other words the man in the computer might ask the user for some information (INPUT). • Example: “What is your name?” The user would then type IN their name! INPUT “What is your name?” www.computerscienceuk.com Inputs → Storage → Process → Output • Then the man in the computer will store the answer in its brain (STORAGE) and think about how to respond (PROCESS). 1. Remember the answer (STORE IT) 2. Think about how to respond (Process) www.computerscienceuk.com Inputs → Storage → Process → Output • The man in the computer would finally respond (OUTPUT). • Example: “So, your name is BOB! What a great name!” The computer would display this on the screen (OUTPUT). OUTPUT www.computerscienceuk.com Inputs → Storage → Process → Output • All programs work in this way… • Think of a word processor: INPUT 1. Users can press a letter on a keyboard (input) 2. The computer stores this event STORAGE/PROCESS and decide how to respond (storage/process) OUTPUT 3. And then display the letter on the screen (output) www.computerscienceuk.com Inputs → Storage → Process → Output • In Scratch, which of the following scripts will help us program the man (inside the computer) to demand an input from a user? www.computerscienceuk.com Inputs → Storage → Process → Output • The ASK script asks the user to enter (input) a value into scratch? www.computerscienceuk.com Inputs → Storage → Process → Output What do you get when you ask a questions? ANSWER! Once you have inputted a value into scratch it is stored in a ‘variable’ called answer. This is what the script looks like www.computerscienceuk.com What is a variable? • In programming, a variable can be thought of as a storage box. • The box may be given a name, and it may hold various different things. • In scratch, is the name of the variable, and it will store what ever you type into scratch. Variable called ‘ANSWER’ Contents is anything we type in www.computerscienceuk.com Inputs → Storage → Process → Output • Which of the following scripts do you think will help us program the man (inside the computer) to output a value onto the screen? www.computerscienceuk.com Inputs Storage Outputs • Which of the following scripts do you think will help us output a value onto the screen? www.computerscienceuk.com The Join Script • We can also join words and the ‘ANSWER’ together to create sentences: www.computerscienceuk.com Summary INPUT SCRIPTS: STORAGE SCRIPTS: OUTPUT SCRIPTS: The “join” script is a nice extra to combine set text with the user’s text to form sentences when outputting to the screen www.computerscienceuk.com Task 1 1. Open onto Scratch 2. Delete the cat and create a stick man sprite. 3. Program it to ask you your age 4. Then get the stickman to reply by saying something like, “Oh, years old is well old! I’m only 30mins old myself!” 5. Then try carry on programming some more questions and responses. 20 minutes www.computerscienceuk.com Moving your Sprite • In programming, things always happen in a set order – a sequence. • Sequences are first written as a flow chart and then programmed in a game. • If we want to move a sprite left the following sequence would have to occur: Press right arrow key In Scratch, we program the sprite like this: Sprite faces to the right Sprite moves a step to the right www.computerscienceuk.com 2nd Activity • Create a new background, something quick and simple. • Program your sprite so that it moves up, down, left and right when you press the arrow keys. If you finish early, be the teacher and help others!! 15 mins www.computerscienceuk.com Plenary • How do you create a sprite? • How do you create a new background? • How do you program movement in the sprite? • Which script allows us to input values into scratch? • Where are our inputs are stored? • Which script allows us to output values onto the screen? www.computerscienceuk.com Homework • Complete the Lesson One Worksheet www.computerscienceuk.com