Www.computerscienceuk.com The Scratch Calculator You are all going to be real computer programmers!!!

www.computerscienceuk.com

The Scratch Calculator

You are all going to be real computer programmers!!!


This Half Term’s Project

• Computer Programming – The Scratch Calculator

Demonstratio

n


Lesson ObjectivesLearning 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


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.


Familiarising yourself with ‘Scratch’

Instructions and Controls Scripts Area

Sequence of Instructions

Sprites

The Stage


Designing a new sprite

Demonstratio

n


Designing a new background

Demonstration


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)…


If a computer is a box…

…think of a program as a man inside the box!


…and programming is all about instructing the man to do what

you want!

“Tell me what to do and I will do

it!!”


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?


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?”



• 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)


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



• All programs work in this way…• Think of a word processor:

INPUT

STORAGE/PROCESS

OUTPUT

1. Users can press a letter on a keyboard (input)

2. The computer stores this event and decide how to respond (storage/process)

3. And then display the letter on the screen (output)



• In Scratch, which of the following scripts will help us program the man (inside the computer) to demand an input from a user?


• The ASK script asks the user to enter (input) a value into scratch?



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



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

Storage


• Which of the following scripts do you think will help us program the man (inside the computer) to output a value onto the screen?



Inputs Storage Outputs• Which of the following scripts do you

think will help us output a value onto the screen?


The Join Script

• We can also join words and the ‘ANSWER’ together to create sentences:


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


Task 11. Open onto Scratch 2. Delete the cat and create a stick man

sprite.3. Program it to ask you your age4. 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


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

Sprite faces to the right

Sprite moves a step to the right

In Scratch, we program the sprite like this:


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.

15 mins

If you finish early, be the teacher and help others!!


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?


Homework

• Complete the Lesson One Worksheet

Documents

Www.computerscienceuk.com The Scratch Calculator You are all going to be real computer programmers!!!