The water cycle. Drip the water drop and his adventure through water. This would good for older students. or grade. This could also be tied into a social studies lesson in order to help understand what is going on as Drip travels along the water.
This water cycle demonstration clearly shows all four steps of the water cycle including evaporation, condensation, precipitation, and collection. What a great, hands-on weather science activity for kids! Gift of Curiosity
Teaching Water Cycle: Activities, Resources, and a FREEBIE
Weather & Climate - This is a great experiment for students to discover the atmospheric conditions that need to be present in order for a cloud to form (warm, moist air, cooling, cloud condensation nuclei).