Refraction: not just glass blocks
Teaching Guidance for 11-14
Any change in medium
Wrong Track: Refraction is when light goes through glass blocks.
Right Lines: Light usually changes speed as it changes medium. Refraction of light is the change in direction of the beam and happens when light changes from travelling in one medium to another, if it does not travel in along the normal.
A sensible approach
Thinking about the learning
There is a tendency for pupils to associate refraction solely with what happens when light passes through rectangular glass blocks.
Thinking about the teaching
A sensible approach here is to introduce refraction by passing light through rectangular glass blocks and then to make explicit links to other phenomena which involve refraction.
- Refraction through rectangular glass blocks.
- Refraction at air–water interfaces.
- Refraction by triangular glass prisms: Dispersion of light.
- Refraction by convex lenses.