If you have an iPad, Lemur is a customizeable MIDI controller that can sync wirelessly with a DAW like Ableton Live. You can program it to controller any parameter you want and is therefore not as limited as a physical controller.
This is a great app that allows you to do side-by-side comparisons of video along with visual and audio annotations that can be sent to students. Check out my YouTube demonstration for a better understanding of how to use this in a music education setting.