As outlined in the paper "The 20 Matchstick Triangle Challenge: An Activity to Foster Reasoning and Problem Solving" by Pat Graham and Helen Chick [EJ1093090], an incredibly useful set of information about the mathematical ability of your students will be revealed. You can look at the way your students try to solve the 20 matchsticks problem, their method of recording, their errors, and also the ramifications of the questions they ask. When your students have completed and discussed the 20 matchsticks problem, they should be ready to tackle the extensions provided in this paper.