Y4 Unit 10: Be a Game Developer

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In 5 minutes :

Unit 10: Be a
Game Developer

In this unit, you use sub-routines and repetition to create algorithms and computer games in Scratch. You will learn:

• about algorithms

• to develop algorithms with repetition

• to test different parts of a program.

Warm Up
Question

Open Ended

The rat must take a certain path to get to the cheese. There is a pattern to the path. What is the pattern?

Complete the first two steps that the rat should take to get to the cheese.
Answer :
a) STEP 1 : Move ?
b) STEP 2 : Move ?

Answer

Step 1 : Move one block down
Step 2 : Move two blocks left

Open Ended

The rat must take a certain path to get to the cheese. There is a pattern to the path.

How many times must these steps be repeated so that the rat gets to the cheese?

Answer

four (4) times in total

Understanding
sub-routines

Sub-routines

• subset of code within a program

• contains instructions that are used more than once in the program

Open Ended

What is a sub-routine? Use your own words to explain.

In computer game

• certain actions that a player repeats throughout the game

• each action uses a sub-routine

Open Ended

What are certain actions in the games that you ever played that seemed to repeat the same thing over and over again? Share your answer below.

Dot sprite in Chasing Game

• move up when the up arrow is pressed

• move down when the down arrow is pressed

• move to the left when the left arrow is pressed

• move to the right when the right arrow is pressed

Open Ended

Table 1 to Table 4 show the instructions when each arrow key is pressed. What do you see in the third step in Tables 1 to 4?

Dot sprite in Chasing Game

• Table 5 shows the steps of the Move Around sub-routine.

• The first step in Table 5 is to define that this is a sub-routine.

• Writing this sub-routine means we do not have to add separate instructions to Tables 1 to 4.

Open Ended

What is the name of the sub-routine in this program?

Open Ended

What is the name of the sub-routine in this program?

Using
repetition

Recap
Question

Multiple Select

There are two types of loops. Choose the correct answer/s.

• Indefinite (forever) loops

• Selection loops

• Definite (repeat) loops

• Control loops

Indefinite (forever) loops

Indefinite (forever) loops

• ​instructions repeat without stopping

• repetition

Definite (repeat)
loops

Definite (repeat)
loops

• ​instructions repeat a number of times before stopping

• iteration

Types of
definite (repeat) loops

• condition-controlled loops

• count-controlled loops

Multiple Select

Two types of definite (repeat) loops. What are they?

• forever loops

• condition-controlled loops

• count-controlled loops

• repetition loops

Writing an algorithm to perform actions using Repeat

​Look at the algorithm below for the second character, Robot, in the Chasing Game. In this algorithm, the Robot character should perform the following actions once:

Open Ended

What would be in STEP 6 if we want the program to repeat in total of 8 times from STEP 3 to STEP 5? Write the sentence for STEP 6 below.

Template Answer : Repeat Step 3 to Step 5 (?) more times

​Answer:

When you write the algorithm for repeat (certain times),
it should be minus 1 (-1)

If we want the program to repeat 8 times from STEP 3 to STEP 5
Answer : Repeat Step 3 to Step 5 seven more times

Open Ended

What would be in STEP 6 if we want the program to repeat in total of 7 times from STEP 3 to STEP 5? Write the sentence for STEP 6 below.
Template Answer : Repeat Step 3 to Step 5 (?) more times

​Answer:

Value in the
Repeat Loop

​What will be the value in the repeat loop?

When you write the value for the loop,
you should plus 1 (+1) as it run through one sequence from Step 3 to Step 5.

Multiple Choice

What will be the value in the REPEAT loop?

• 8

• 7

• 9

• 6

Multiple Choice

What will be the value in the repeat loop?

• 10

• 9

• 8

• 7

Multiple Choice

What will be the value in the repeat loop?

• 7

• 5

• 3

• 4

• ​Do individually / group (10 minutes)

• Teacher will reveal answer/discuss the answer

Dot sprite in Chasing Game

• Create this program in Scratch.

• Sub-routine

  • My Blocks > Make a Block > Name the block > Ok

• ​Go to "My Blocks" and make a new block

• Give your sub-routine a name and press OK

• Name should describe the purpose of the sub-routine

  • Draw Triangle

  • Ask Number

• Below the "define" block, add or complete the code you want to run when the block is called or executed

• Call or use the block in your program

​​How to make a sub-routine