Y4 Unit 6 Part 1 : Be a Musician

In this unit, you will create music with repetition using Scratch.
You will learn:

• to predict the outcome of algorithms that contain repetition

• to compare and contrast algorithms designed for the same task

• to develop programs with iteration.
  

​whole note

​half note

​quarter note

​eighth note

• ​Forever Loop (Unit 1)

• Repeat Loop (Unit 4)

• Repetition in Scratch uses either the forever loop or the repeat loop.

• Algorithm A with forever loop

  • What sprite do we use?

  • How to start the program? What do we pressed?

  • How does the program end?
    

• Algorithm B with repeat loop

  • What sprite do we use?

  • How to start the program? What do we pressed?

  • How does the program end?
    

In a forever loop

• instructions are repeated over and over without stopping

In a repeat loop

• instructions are repeated a set number of times

• ​In Scratch, each sprite can play different sounds.

• The minus sign (-) means decrease

The lowest volume in Algorithm D is 20.

• The volume decreases by 10 in each loop and there are 8 loops in total.

• The starting volume was 100,

  • so 100 - (10x8) = 20

We want to repeat the song until the space key is pressed. Look at the two Algorithms E and F.

• Which algorithm is better?

• Why?

• Algorithm F has a total of ten steps and repeats the song until the space key is pressed.

• Algorithm E has a total of twelve steps and plays the song forever.

• Algorithm G will use more blocks of code to create the program.

• Algorithm H will save time in writing and creating the program.