Sure, those puddles disappear and their bathing suits dry in the sun, but kids often don't give those everyday happenings much thought. When trying to teach or explain evaporation to your kids, nothing is better than seeing it in action. However, with purposeful activities or experiments, your kids can predict, observe, record and discuss what is happening so they understand the concept of evaporation.
Fill two clear, identical containers about one-third to one-half with water. Cover one with a lid or plastic wrap and leave the other open. Mark on the outside of the containers at the water lines, using masking tape so you can record the time. Have children predict what will happen to the water in each container after 24 hours. Mark and date a new line every day. For older kids, measure the height of the water and record it on a chart. Check the containers the next day and continue checking and recording until one has completely evaporated. Alternatively, place open containers of water in different areas under various conditions, such as on a sunny window sill, in a cool closet, under a shade tree and on a sunny porch, to observe which one evaporates the fastest. Older children can graph the results.
After a rain, let your little scientist take a picture of a puddle on a nonporous surface such as a driveway or sidewalk. Record the time. Every two to six hours, depending on the size of the puddle, temperature and sunlight conditions, take another picture at the same angle, using the same zoom. Continue to take pictures and record the time until the puddle evaporates. Print out the pictures and create a time line of the evaporation process on poster paper. You can also take more pictures, such as once an hour. Then after printing them out, flip them like a cartoon book to watch the puddle evaporate right in front of your little one's eyes.
On a hot, sunny day, hand your kids sponge paint brushes and cups of water. Ask them to paint a sun and time how long it takes to disappear. Discuss why one kid's sun took longer to evaporate than other suns. Perhaps they used more water or had a bigger paint brush. Perhaps they were standing so it shaded the picture. Next, ask them to paint a sun and a house. Add more and more to the picture so it begins to evaporate before they are finished. Have fun with this activity, challenging kids to write messages to eat other or do math problems before they disappear.
More Evaporation Activities
Boil water in a pot or in a tea kettle. Watch the steam disappear into the air. Where did it go? Can the kids feel the extra water in the air a couple feet away? If your stove has a cabinet or microwave overhead and the steam settles there and forms water droplets, it shows more steps of the water cycle for your kids to discover. You can also hang laundry out to dry and check every 30 minutes to check how wet or dry they feel. Hang some in the shade and some in the sun. Alternatively, place an ice cube outside in the sun and watch it melt, then evaporate. If possible, collect some snow in a clear container and bring it indoors to watch it melt, then evaporate. Wipe down your counters or mop the floor and wait for it to evaporate.