In the past, I’ve used ripple tanks to get my students to develop the conceptual understanding of waves, and to see some of the key effects – reflection, hard-edge diffraction, etc. The modeling curriculum, however, uses ripple tanks to develop an intuition for Snell’s Law. So today we brought out our ripple tanks, set them up, and looked for a change in the direction of wave propagation when water surface waves pass to a new medium.

The next step is to use semi-circular acrylic disks to derive Snell’s Law, but I am not sure we have time for the full modeling cycle on this one. I think the students got a pretty good understanding of the effect today, so I think this topic will get IB brevity instead of Modeling depth. Here is my attempt to photograph the refraction effect.

It’s strange when you need to turn off the light and let the students discover things with apparatus in the dark. I coukdn’t keep an eye on everything, and ended up getting into some really deep series of Socratic questioning as I circulated. I suspect the dark lab meant decreased time on task, so perhaps I will need to come up with a better solution for our diffraction/interference patterns work later this week.