A vet has weighed three of his cats - Tibbles, Nibbles and Scribbles. Tibbles and Nibbles together weigh 7kg. Nibbles and Scribbles together weigh 8kg and Tibbles and Scribbles together weigh 11kg. He challenges students to find the weight of each cat individually.

First broadcast:
14 September 2007

Students could work in pairs or groups to solve the problem. They could discuss strategies and work through ideas with the trial and error approach. The pairs or groups could also report back before the final part of the clip.