Activity 4: The Water Cycle is part of Introduction to the Atmosphere, which is Section 1 of the Cycles of the Earth and Atmosphere module created by the University Corporation for Atmospheric Research. This module consists of lesson plans and supplemental materials created specifically for middle school teachers. In The Water Cycle, a model is used to investigate the various components of the cycle. The directions are written as a classroom demonstration; however, with sufficient supplies, groups of students could each construct their own model. The activity provides observational questions and sample answers. In addition, assessment ideas, which include an additional challenge, have been provided. The lesson plan can be completed in 1 to 2 days.