Makey Makey is an invention kit that can turn everyday objects (anything that has a little conductivity) into a touchpad. You can also program your Makey Makey with something like Scratch, Tynker or Aduino. This can integrate really nicely with Science investigations into conductivity.
Introduction to Makey Makey
Makey Makey Piano
Makey Makey Bongos
Makey Makey Tetris
Scratch & Makey Makey Intro
Makey Makey Apps
Maker Spaces - Makey Makey
Fishpond Makey Makey Kits
Modern Teaching Aids - various kits including multiple sets.
AliExpress Makey Makey Kits - be aware some may not be genuine Makey Makey. This is the cheapest option.
Note: If you already have alligator clips and mini-usb cable you could start with just a Makey Makey board if wanted.
Makey Makey & Scratch Drum Kit
Scroll down to see a Scratch Piano see the code here
Video Gallery of Examples
Scratch Makey Makey Drum Machine Code - click on the instruments in the bottom left to see the code for each.
Makey Makey Scratch Projects - select a project then click See inside to view the code.
Video of Makey Makey in action