Lesson: The Water Cycle

Prerequisites:

Objectives:

Prepare terrariums for initial observations
Use terrariums to connect concepts of precipitation, condensation, and evaporation into a unified water cycle concept

Materials:

Have each student supply their own plastic salad container from a fast food restaurant or some similar clear plastic container. (A ziplock baggie will work if there are not enough salad containers available.)
soil
water
spray bottle
large sunny window or grow light
fast and reliably germinating seeds (marigolds, herbs, lima beans, etc.)

Introduction:

Ask: "What are clouds? What are they made of? What is rain? What does the sky look like when it rains? Why does it rain? Where does the rain go after it falls? What happens to puddles after it rains?" Get a discussion going about the different parts of the water cycle: evaporation, precipitation, and condensation. Use as many questions as possible to determine which concepts the students may understand and where any misconceptions may be.

Body:

Assemble the terrariums: Have each student build his/her own terrarium by putting about an inch of soil in the bottom of their plastic container, planting a seed according to the package instructions, and giving a thorough soaking of water. The initial watering should be all that is necessary since the plastic container will create a closed environment which will not allow the water to escape into the atmosphere. Label the terrariums and put them in a sunny window or under a grow light.
Observing the terrariums: Have the students make observations about their terrariums each day and record their observations in their weather journals. Try to do the observations at different times each day. Have the students record what they see in writing and/or in pictures. Discuss as a class anything the students observe. Continue this throughout the lessons on the water cycle (evaporation, condensation, precipitation).
Proceed through the following lessons in this order : evaporation, condensation, precipitation.

Conclusion:

Possible questions to ask the students: "We only watered the soil in our terrariums once; how did the water get on the lid? Take your lid off the terrarium and feel the soil. Why is the soil still wet? Do you think that any water has evaporated from the soil? Why? If water evaporated, where did the evaporated water go? Did it ever rain in your terraium? How do you know? Where did the rain come from? Is there anything in your terrarium that reminds you of a cloud or cloud drops?"

Teacher may want to make a connection between the water cycle in the terrarium and in the real world with a discussion using the following: "If the terrarium is a model of the real world, what do you see outside that reminds you of the plant in our terrarium? reminds you of the soil in our terrarium? reminds you of the small water droplets on the lid? The soil in our terrarium stays moist, the ground outside never dries out completely. Why? What keeps it moist? Water collects on the lid of the terrarium, water also collects in the sky as clouds, where does the water in the clouds come from?

Vocabulary Words:

none

Evaluation:

In the students make a picture model in their weather journal which represents their terrariums. Have the students include all the parts of the terrarium like, container, soil, water, lid, plants, etc. Also, have them draw and label the processes (evaporation, condensation, precipitation) they see happening and their locations in the terrarium.
Have the students complete the water cycle page in their weather journal by labelling the evaporation, condensation and precipitation processes.