The tricky thing about this topic is that we are dealing with activity at a sub-microscopic level. In order to explain to students what is going on we need to use models, images, animations or simulations.

Whilst the Internet is a valuable resource there are many animations or simulations which are not fit for purpose. Equally not all printed resources will allow you to fully explain such ideas to your students.

It is essential that if you decide to use such resources with your students that you evaluate them in detail first.

In this section you are provided with two resources designed to support teaching and learning. Ideally you should compare both resources. However your computer's security setting may prevent you or advise you against running the simulation as it uses Java. Therefore it may only be possible to evaluate the downloadable printed resource.