Using MIT Scratch for Programming and Control

Exercise 6 – Creating a Scratch Packman

Year 9 ICT

Autumn Term 2007

What you will learn:

• To design a maze background• To resize a sprite• To move a sprite under keyboard control• Stop the sprite moving over the background• To get ‘prizes’ to disappear• To score with the prizes• To get the prize to appear again unexpectedly• To choose your own prizes• To randomly alter the grid.

Stage 1 of Packman

Maze

Explorer‘Prize’

Score

Stage 2 of Packman

Explorer moves

Stage 3 of Packman

Explorer grabs prize

Score goes up

Stage 4 of Packman

Explorer moves on

Stage 5 of Packman

‘Prize’ reappears

What you need to decide

• To decide on a maze background grid.• To decide on the sprite as the explorer.• To plan the ‘prizes’ – the sprites and the points

for each.• To plan for how long a prize would disappear.• To decide if the background will change to a new

level or will the grid alter randomly.

Design a background

• The background must have one colour that the sprite cannot cross (blue in the example.)

• The passage ways must be broad enough to take the sprite.

Replace the Cat

1. Delete the cat sprite.2. Choose a new sprite

– use the central button under the stage. I called it the explorer.

3. Resize the sprite to make it small enough to follow the passages.

Step 2 Step 3Step 1

Get the Sprite to Move

• Use the starting code as below – make sure all directions work.

Keep the Sprite on Track

• Stop the sprite moving over the background by …

• … checking if it has moved too far.

• If so, move back 5

Add a “Prize”

• Add a “prize” – a banana.

• Place it in a passageway.

• There should be a forever loop

• The script should hide the banana if it is touching the explorer.

• Remember to save your Scratch program.

Score Grabbing a Prize

• There are 2 parts

• A variable to store the score

• The score needs to increase when the prize is grabbed.

Restore the Prize

• The banana needs to reappear and at a random time makes a difference.

• Use the pick random 1 to 10from Numbers

• Put it inside a wait.

• Decide on the longestand shortest waits

• Remember to save your Scratch program.

Introduce another Prize

• Introduce other sprites as prizes.

• Resize and add the correct script to each.

• Choose where each is to go, what effect it will have on the score, how quickly each should reappear.

• Remember to save your Scratch program.

Make your code efficient

• The script to stop the sprite going onto the grid might be more efficient.

• Do you have this section only once?

• Are there any other parts to be improved?

Further ideas

• Does the score set to zero for each game?• Is there a time limit or a target score?• Further sprites could be added to block/unblock

sections of the grid.• This could make the game change as it is

played.• There could be different levels with the

background changing after a time.• There could be tunnels which move the player to

a new maze background …