Science presenter Jon Chase explains the refraction of light. He demonstrates how refraction can make the handle of a Pyrex jug seemingly disappear. He explains this is because when light travels through two substances with different refractive indexes, it changes direction at the boundary.
The class could investigate refraction using ray boxes and blocks of Perspex or glass. The demonstration in the clip could be repeated using vegetable oil and Pyrex, including laboratory glassware. It is most impressive when repeated using a very large beaker and a smaller beaker.