For Kids

Science Experiment: Hydrologic (Water) Cycle - Make a Terrarium


The Great Big Water Cycle Adventure

All of the water on the earth is in constant motion. Water falls to the earth as rain and then evaporates back up into the air making clouds. Then the water falls back down to earth again as rain. This cycle is call the hydrologic or water cycle.

To see how the hydrologic cycle works you can make your own little model of the earth in a terrarium. A terrarium is a little garden inside a clear, sealed plastic or glass container. A canning jar is a common glass container with a lid that might be easy to find at home. All of the supplies to go inside the terrarium to grow a plant or two can probably be found in your backyard or in your neighborhood. Small stones go in the bottom of the container. Then add a thick layer of soil. You can buy small plants at a garden center but you can also find some right in your yard. Look in shady areas for moss, it grows really well in a terrarium!

What You Need:srpterrariumparts

  • a Clear Plastic or Glass Container With a Lid
  • Stones
  • Soil
  • Plants
  • Water Little Toys for Decoration (optional)

After planting, add enough water just to moisten the soil. You don't want to flood your garden. You don't want standing water in the bottom of the container. When you poor water into your terrarium that is the beginning of the water srpterrariumsingle1cycle. You essentially have made it rain in your little glass world! When you set your terrarium in the sun the water inside the terrarium heats up and turns into water vapor in the air. This is called evaporation. When the water cools back down, it turns back into a liquid. You will see condensation - water droplets - sticking to the lid of your terrarium. If the drops get large enough, they will roll down the sides of the container or fall from the lid - rain!

srpterrariumcloseup31The close-up on the left shows the condensation that began to form on the inside of the jar after only 1 hour sitting in the sun.

If there is too much water just open the lid and let some of the water evaporate. If your plants look wilted or dry, try adding a little more water. It might take some trial and error to get the amount of water needed just right.

Science Experiment Idea: Make three identical terrariums. You have to use the same kind of container, the same amount of soil & the same plants. Make your variable (the thing you are going to test) the amount of water you put into the terrariums. Measure a different amount of water into each terrarium. Close the lids and watch the terrariums over several days to see which amount of water made the best environment for your plants. A terrarium with too little water will have dry plants. A terrarium with too much water will have plants with yellow leaves and maybe even mold growing on the soil!

Websites, Activities & Printables:

Science in Context

Science in Context: Water Cycle and Terrariums is a database you can use in any IndyPL Library Branch or at home. Login using your IndyPL library card number. The Science in Context database will show you articles, images and videos to help you learn about the water cycle and terrariums.


You can also ask a math and science expert for homework help by calling the Ask Rose Homework Hotline. They provide FREE math and science homework help to Indiana students in grades 6-12.


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