Great simulations!

I used this in class today.  It were awesome and the kids loved watching the wave as we talked about what was happening.  When they finished their worksheet (see previous worksheet on waves) they were allowed to come over to my computer and manipulate it themselves.  I thought I'd share them here.

https://phet.colorado.edu/sims/wave-on-a-string/wave-on-a-string_en.html

This website also has many different simulators, mostly demonstrating properties of physics.  There are a few other simulations for chemistry and biology as well.

https://phet.colorado.edu/en/simulations/category/physics/sound-and-waves

I hope you find it useful!  I used another from this website called "Sound." It allows you to change the frequency and amplitude while you listen to the sound and watch the compression/longitudinal waves coming from the speaker. Pretty cool.