Scratch can play three types of audio - sounds, drums and instruments. Sounds are recordings, such as WAV or MP3 files. Drums and Instruments are based on general MIDI notes.
Write a recognisable tune using this technique. Vary the notes and durations to create the basic melody.
Using the same action (ie, pressing a particular key) as the trigger, write a second stack of notes that play simultaneously so that they create a harmony, ie, two melodies that play together.
Build a tune that has more than three "parts" that play together. Use different instruments to add variety to your music. Now it's getting complicated!
Use control structures such as loops to repeat sections of music in order to create a complete song (ie different verses and choruses)
Expand your song by including a drum track using the Play Drum block. Remember to keep everything in sync!