Superposition
http://physics.bu.edu/~duffy/HTML5/interference_of_pulses.html
Investigate speed, frequency wavelength, sound
http://www.physicsclassroom.com/Physics-Interactives/Waves-and-Sound/Simple-Wave-Simulator
Superposition
Make waves on a slinky, add tension, density, drag
http://www.physicsclassroom.com/Physics-Interactives/Waves-and-Sound/Slinky-Lab
Diffraction
Wave properties
Interference