User suggestions: NGSS standards

[oliver-phet]

I have a few suggestions for that Waves intro, though, that could make it more useful, particularly as we try to use these simulations for virtual curriculum around NGSS standards.

I tried to order these from potentially the easiest to the hardest to implement:
For sound and light, could we have numerical values for the frequency? Students could use those to graph the data (along with wavelength) and find the speed of light/sound (this would be my top priority and the inspiration for this message)
The speed of light/sound could also change with an option to change the medium? Just 3 options, like air, water, and empty space could be cool, the sound of course wouldn't work in space...
In the 'light' section, a temperature sensor on the screen could also help relate the different energy levels of the different colors, which would allow for another experiment that students could design with this.
On the frequency slider, could we have infrared and ultraviolet waves that are not visible? That could help make it more clear that those are light also, just not visible light, but could still change the temperature.
Finally, and this seems least likely, but it'd be cool if at least the sound simulation had the opportunity to move the sound and experience the Doppler Effect. Doing it with light would be awesome too!