Game: What's the Rule

From the BC Girl Guides STEM Math Challenge.

This is a great game for filling gaps in a camp or event schedule. Keep a collection of small objects handy and pull it out when you're waiting for a meal, waiting for the rest of your group to arrive, waiting for a bus, waiting for the rain to stop...


  • 15-20 small objects: crayons, paper clips, bottle caps, bandanas, shoes, coins, pocket lint--whatever you have handy


  1. One person selects a few objects according a rule that she makes up. For example, she might choose things that are yellow, or things that are longer than her pinky finger. She puts her selected objects in a group separate from the rest of the objects, but she does not disclose her rule for choosing them.
  2. Everyone else in the group tries to guess the rule.
  3. If the guessers need hints, they can ask if one of the remaining objects could go into the selected group. The person who did the selecting can only answer "Yes" or "No".
  4. When someone guesses the rule, put all the objects back together. The person who guessed the rule then gets to select objects based on her own rule.