Parents typically take it for granted when a puddle is here one day and gone the next. Children, however, will marvel at this magical event, wondering where in the world that puddle went! Instead of dismissing his curiosities, use the opportunity to teach him about important scientific concepts. Point out evaporation in action when it rains, when the snow melts or when the rug dries after your preschooler spills his juice. Again.
Fill two identical jars with equal amounts of water. Help your preschooler mark the water line with marker or tape on the outside of the jar. Cover one jar with a lid or plastic wrap and leave the other jar uncovered. Place the jars next to each other in a location where you and your young scientist can easily observe them over the next several days. Observe and talk about the changes that begin to occur within a day or two. Ask your child to write or draw about what is happening as the water in the uncovered jar begins to decrease due to evaporation. Encourage your child to be curious by acknowledging all observations, including those that have little to do with the actual point of the experiment -- Mom! There's dirt on this jar and not on the other one!
Drying laundry outside is a perfect lesson in evaporation. If you're more of a "throw-em-in-the-dryer" type, don't fret, you can still show your child the wonders of evaporation. Wet a washcloth and hang it on a towel bar or the side of the bathtub, or hang a few wet items on the back of a chair to observe over the next several hours. As you monitor the items drying, talk about what is happening (evaporation). Introduce your child to the factors that influence evaporation (heat, sunlight, wind) by placing one wet item in a cool, dark place and another in a warm, sunny place to compare and contrast the drying times. This might also be the perfect time to bring up the rule about never throwing your wet towel in the corner of your closet to dry, because it won't!
Let nature be the teacher as you step outside after a rain shower. Find a few puddles with your child, noting their size and location or taking a picture of them. Monitor the puddles over the next several hours. Evaporation takes time and you don't want anyone losing interest, so let your child play in the puddle, throw rocks into it or push his trucks around. As the sun heats up or the wind kicks in, talk about how those things help the puddle evaporate. When you check in on your puddles, note the difference in size or take another picture to compare to the first. Point out when the puddle is completely gone, letting your child be impressed by nature's magic.
Ice Cube Challenge
Implement a friendly family competition to teach evaporation. Give each family member an ice cube in a plastic zipper bag and challenge them to be the first to get their cube to melt. Avoid disaster by laying out the safety rules -- no open flames, matches or blow torches without parental supervision. Enjoy the scene as your little scientists come up with creative ways to get their cube to melt. If they need inspiration, point them in the right direction by suggesting they place the cube in a warm location (on top of a running dryer, in direct sunlight, near a heating vent) or perhaps their hot little hands are the warmest place around. Once the cubes have melted, open the bags and place them on a shelf to watch the evaporation over the next several days.