In this optional lesson, students apply their understanding of volume to relate the amount of water that falls on a house roof to the amount of water a family might use for everyday activities. This lesson is optional because it requires conversions between different measurement systems, which goes beyond expectations for grade 5. The calculations, especially those for family water use, require detailed estimates. Students can make their own estimates to increase the modeling aspect of the activity or they can use provided estimates. Students may consider a variety of uses of water beyond those highlighted in the materials, such as the water they drink or the water used for plants.

In the last activity, students compare the volume of water that falls on a house roof to the amount of water used each month. In the process they discover that length and volume units in the metric system are naturally related to one another, and the context gives students a chance to practice multiple conversions.

What do your students think it means to be good at math? How are you helping them change negative impressions they might have about their ability to reason mathematically?