In the study of radioactivity, student practicals are difficult to organise because of the hazardous nature of the topic, but this apparatus offers students the opportunity to obtain realistic results in a perfectly safe way. The student set contains ten bowls and 500 small plastic cubes. The cubes have one face identified and represent radioactive nuclei which have ';decayed' when this face is uppermost. Ten groups shake their set of nuclei and roll them out onto the bench. For each throw the decayed nuclei are counted and removed from the set. Excellent results for an exponential decay curve are obtained with increased awareness of the link between activity and the number of nuclei present.

• Each set contains: 10 trays and 500 small plastics cubes