water cycle

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Home : 2003 : July : 22

water cycle
By Julianne

You can study it first in a book and follow up with an experiment, or you can start with the experiment and follow up with a book review. I like to start with the experiment because it gets the kids excited about the subject.
Here's one I've used for water cycle:
Cut a 2 liter pop bottle in half about 4 inches from the base. Using potting soil and seeds or a small plant, make a terrarium in the bottom portion of the bottle. Water it and squeeze the top portion of the bottle inside the bottom to make a dome. You can also just tape the two halves back together using clear packing tape. Put the terrariums

in a light window - not too much sun or you'll bake the plants! Let the kids predict what they think will happen. Have them guess how much they'll have to water, how tall the plants will grow, what will happen to the container, etc. Let them come up with the questions to ask. What you should notice as time goes by is that the inside of the dome gets misty and the plants continue to grow without the use of additional water. As a control, you can leave the lid off one of the planters. Water it as often as you water the terrariums. What do the kids think the difference will be? Watching the condensation/evaporation cycle in this way allows for some real discussion about what is happening and how it works. From there the books will fill in the gaps.