Www.computerscienceuk.com Learning the skills for programming Advanced Visual Programming

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Learning the skills for programming

Advanced Visual Programming


Quick Review of Last Lesson

Event Driven Programming

Blocks of code can be run when certain events occur

Random Function

In Scratch there is a function to pick a random number


• Learning Objectives– Remember what is meant by “event-driven” computer

programming– Remember how to generate a random number in scratch– Understand what a variable is– Understand how computer make decisions (IF

Statements

• Lesson Outcomes– Produce a Magic 8-Ball program

Literacy – Key Words

Variable A place where programs store data – think of them as storage boxes.

IF Statement The code needed to get programs making decisions.


Variables• If you were playing a game

and rolled a dice, you would need to memorize the number and then use the number to move your counter around the board.

• When programs work with data they need to memorize things too (even if its just for a second).

• Programs don’t have brains to store their data, instead they have variables.

I rolled a 6 – I must

remember that so I can move my counter

?


Hands up if you can explain what a variable is?


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 a ready made variable, and it will store what ever you type into scratch.

Variable called ‘ANSWER’ Contents is anything we type in

Storage


Creating New VariablesBut we can also create our own storage boxes (variables)

To create a variable we:- click on the

variables button

- Make a variable

- Give it a name

We can then set the box to a particular value – in other words“put some data in the

box”


Variables - Summary

Variables are the name of the boxContents is any data the program needs to keep hold of

Variables are storage boxes which programs use to hold/store data

Programmers can create as many variables as they like.


Hands up if you can explain what a variable is?


Hands up if you can explain how IF statements work?


IF statements are how programs make decision.

IF this occurs, I will do this

ELSE, I will do that

IF – ELSE statements allow programs to make decisions based on certain conditions occurring.


The IF Statement

What is this script going to do?When we click the sprite a random number is generated and

stored in the variable called ‘number’. If number = 1, the cat will say “ your random number is 1”.

If number = 2 the cat will say “ your random number is 2”.


Hands up if you can explain how IF statements work?


Magic Eight Ball• You shake

them and they give you a random message – they are fortune tellers!

…and you are now going to program one!


Planning before we program

• Before programmers start programming, they always start by imagining the program as a real life object, as a human perhaps.

• If you were a magic 8 ball what would you do?

1. Wait to be shaken2. Pick a random statement3. Say the random statement

Write down your thoughts on a whiteboard


If you were the 8-ball program, what would you

do?• Wait for user to shake 8-ball

(Event / Input)• Random number would then

be generated• You would memorize the

number (store it)• You would decide what the

number means (process it)• You would then output a

message based on that random number

INPUT

STORE NUMBER IN VARIABLE

What does a 1 mean?

OUTPUT Message


Planning

INPUTWait for user to shake 8-ball (Event / Input)

HOW?


Planning = AlgorithmRandom number would then be generated

You would memorize the number (store it)

HOW?

STORE NUMBER IN VARIABLE


Planning = AlgorithmYou would decide what that means (process it)

HOW?

What does a 1 mean?


Planning = AlgorithmYou would then output a message based on that random number

HOW?

OUTPUT Message


Task

• Create your own Magic 8-Ball program– It must have an image which the user can

click–When its clicked it must select a random

statement and display it on the screen

• Extend by developing the look of the program – improve the image, background or even animate the ball.

Documents

Www.computerscienceuk.com Learning the skills for programming Advanced Visual Programming