Combinations, often thought of in terms of possibilites, is an important mathematical topic for young children. They are called upon to think logically, to develop strategies, to organise results and to communicate clearly. Each of these processes can be approached and tackled in a variety of ways. This allows children to enter and exit the problem and to engage with it in appropriate ways and at an appropriate level. Teacher's questions around results will scaffold children's thinking and move them along in their efforts and strategies. Subsequently, children can be asked to use higher order, or critical, thinking skills to assess and evaluate the effectiveness and efficiency of the different strategies.

This Let's Investigate problem is topical for the season of Halloween. Even if Halloween is not part of the local culture, setting problems within such a context is an opportunity to talk about the celebrations and traditions of other cultures.

Each step of the problem introduces another level of complexity, as the number of possibilities grow. This establishes the need for results to be ordered to avoid repetitions or omissions. Some children will need to draw and cut out the costume pieces and then put them together. Checklists can be used while others, operating more abstractly, can be guided toward making a table or matrix to listing and combine the items or find the permutations.