Press each key on the the one octave piano and make music! The grey buttons on the top play background music. The green button stops the background music. P.S. the black keys don't work unfortunately because scratch doesn't have major or minor audio options for piano notes.
I recently learnt how to play the piano, obviously its more complicated than one octave but i just thought it was fun! Sorry that it's only one octave, scratch doesn't have audio of higher or lower piano notes than these.