Observe sand or mud closely and learn what it is made of.
Science content (2016 curriculum):
Earth/Space: Landforms, Erosion (3)
Earth/Space: Rock cycle, Earth Materials, Natural resources (5)
Science topic (2005 curriculum connection):
Earth and Space Science: Air, Water and Soil (grade 2)
Earth and Space Science: Renewable and Non-Renewable Resources (grade 5)