What's Evaporation?



This lesson developed by Leona and Jim Meeks
Recommended Age: Preschool and Early Elementary



Question

What is evaporation?



What You Need

  1. Clothesline outside or inside
  2. Clothes pins
  3. Clothes like t-shirt, sock, pants, wind breaker or plastic like pants/shorts
  4. Bowl
  5. Water
  6. Hair dryer



What You Do

Experiment #1: Clothes on a Clothesline


  1. In a wash basin or sink, thoroughly get the articles of clothes wet.

  2. Wring them out to get out excess water.

  3. Hang the clothes outside or inside on your clothesline.

  4. Check out the clothes every hour or so. Touch and feel them.

Experiment #2: Bowl of Water

  1. Fill a bowl half full with water.

  2. Put the bowl on a table top or shelf.

  3. Check out the bowl every few hours for a couple of days.


Experiment #3: Hurrying Up Evaporation

  1. In a wash basin or sink, thoroughly get a sock and a nylon piece of clothing wet.

  2. Wring them out to get out excess water. Put the clothes on an inside clothesline or drape them over a chair.

  3. With an adult, plug in a hair dryer. Turn the hair dryer on and direct the warm air onto the clothes.

  4. Check out what happens.



What Is Happening

Water is constantly taking on different forms on our earth. Water comes down from the atmosphere as rain, snow, or sleet and hail. The ground absorbs water and much of the water drops into lakes, streams, ponds, rivers and oceans. Then the water does w hat we call "evaporate." This means that little tiny droplets of water get absorbed back up into the air.

When we get clothes wet, the material has absorbed and sucked in water. We could feel the clothes and we could tell they were no longer dry but rather very wet! When we left the clothes out in air on the clothesline, something happened! The water in th e clothes went away! Evaporation was happening! The water droplets in the clothes were absorbe and taken back into the air.

Evaporation is a process and it takes time. You could see that some articles of clothing dried faster than others. Small articles of clothing dried faster than larger and bigger ones. The kind of material in clothing also makes a difference as we can s ee that nylon and plastic kinds of material dries faster than cottons. Thicker material absorbs more water and so will take longer to dry and thin material.

In the bowl, we could see that the water level kept getting lower and lower. The water seemed to disappear. That is just like what happens in rivers, streams, ponds, lakes and oceans each and everyday. Water is absorbed back into the air by the process of evaporation. Have you ever seen a lake or pond in the summer when we have had a long period of time with no rain? The level of water goes down and down.

When you used a hair dryer on the articles of clothing, you were speeding up the process of evaporation. You can see this happening when you wash your hair. If you let your hair dry naturally, it takes awhile. If you use a hair dryer, your hair dries m uch faster! People with thick and long hair need more time to dry their hair. Like we saw with clothing, thick and long hair absorbs and sucks up more water than thin and short hair.

Watch mud puddles after a rain storm. Or watch what happens to sidewalks and roads after a rain. The water seems to disappear. It is evaporating!