IT Qual - Scratch Variables

• Computing
• Upper Secondary (Key Stage 4)
• GCSE

Scratch Variables

My expectations

It's ok to be wrong

Listen when others are speaking

Recall

Repeating steps in programming is called iteration. But you know it is as a different term?

Recall

Repeating steps in programming is called iteration. But you know it is as a different term?

Loops or Looping

Recall

What is the difference between these two blocks?

Recall

What is the difference between these two blocks?

One repeats code inside the block 10 times while the other repeats it forever.

This Half term

Introduction to scratch

Variables

Selection

Iteration

Lists

Games Design

Learning objectives

Know what a variable is

Know how to use variables in Scratch

Dictionary definition of a computer variable

"a named memory location in a program that stores a value that can change"

What would the new value of score be after running these three blocks of code?

What would the new value of score be after running these three blocks of code?

2

Orange* blocks of code in Scratch are called Variables.

*we will see later that some variables are set in different colours.

Variables are places in a program to store data that you might need later on.

They can change as the program runs.

You could use this variable, score, to keep track of the score of a game for example.

What other variables could you think of that might be useful for a game?

What other variables could you think of that might be useful for a game?

What other variables could you think of that might be useful for a game?

Score

Points

PlayerName

Goals

Lives

Shots

Time

Speed

PREDICT

Predict what you think will happen.

Predict what you think will happen.
Write down your predictions.

RUN

Click this link or visit 

https://scratch.mit.edu/projects/1084991660/  to run the program

Were your predictions correct?
Did anything surprise you?
Did your predictions miss anything out?

INVESTIGATE

How do the following two blocks of code relate to each other?

How do 'ask_name' and 'define ask_name' relate to each other?

INVESTIGATE

When your program reaches the ask_name block, it calls the subroutine ‘define ask_name’.

‘define ask_name’ is a sub program

or a function.

INVESTIGATE

What happens if you remove 'ask 'what is your name' and wait'

How do 'ask_name' and 'define ask_name' relate to each other?

INVESTIGATE

What happens if you remove 'ask 'what is your name' and wait'

Big Ed will now only say “Hello”.

As the question has not been asked, there is no ‘answer’.

The line ‘set name to answer’ will now give name an empty value.

INVESTIGATE

Below 'define ask_name'. There are two variables being used

Below 'define ask_name'. There are two variables being used. What are their names?

INVESTIGATE

Below 'define ask_name'. There are two variables being used

INVESTIGATE

Why do you think this code only says “Hello” and not “Hello” and the name you entered?

Why do you think it only says “Hello” and not “Hello” and the name you entered?

INVESTIGATE

Why do you think this code only says “Hello” and not “Hello” and the name you entered?

It is because ‘name’ is being linked to ‘answer’ before the question is asked.

You must always set the value of a variable before using it.

MODIFY

Modify the code that’s already in the program.

Make

Use the code blocks to add a new question to be asked about your favourite sport or hobby.