Scratch has commands that enable you to play tunes. 

Mozart's Twinkle Twinkle little star is quite easy to construct. The musical notation for this is below: (obtained from http://en.wikipedia.org/wiki/Twinkle_Twinkle_Little_Star)

The following image of a musical stave maps the numeric values for the notes on the music

This allows the following code to be created (with a little thinking).

Complete the rest of Twinkle Twinkle Little Star.

Change the instrument being played and try to synchronise some drums to the tune. 

Use loops to draw a pattern while playing the tune. 

This activity has been adapted for student use from a wiki being developed by Mike Lieshman and other contributors at http://cscos.pbwiki.com/