Waves can be reflected at the boundary between two different materials. • Waves can be absorbed or transmitted at the boundary between two different materials. • Students should be able to construct ray diagrams to illustrate the reflection of a wave at a surface. • Students should be able to describe the effects of reflection, transmission and absorption of waves at material interfaces. • Required practical activity 9 (physics only): investigate the reflection of light by different types of surface and the refraction of light by different substances.