Explore bending of light between two mediums with different indices of refraction. See how changing from air to water to glass changes the bending angle. Play with prisms of different shapes and make rainbows.
I’ve tried this and it is a very good simulation, allow students to explore not only how light bends on refraction, but why. A variety of meters make for many possibilities for virtual lab lessons. I plan to use it when I next teach this section of my physics class.