Losing Your Marbles?

Losing Your Marbles? is a Grade 5 measurement investigation that uses two cylindrical jars to estimate an unknown number of marbles. Teams begin with mental-math estimates based on a smaller jar with a known count, then measure the height and radius of both cylinders and compare their volumes to refine the estimate. The actual marble count at the end provides a concrete check on the reasoning.

Use it in small groups when students are studying volume, estimation, and proportional thinking. Comparing the first mental estimate with the volume-based estimate creates a strong discussion about what information improves a prediction. Create a free Find a Math Game account to generate teacher-ready lesson support for Losing Your Marbles? No credit card, with 3 lifetime lesson generations.