What Is This Activity?
What happens to the water after it rains? It doesn't just disappear! In this activity, kids experiment to see how sun, shade and wind affect how water evaporates. They also see where water goes when it evaporates. This activity works best on a warm, sunny day. If it is damp or raining, check out "Play With Puddles" in the "Explore Some More" section at the end of this activity.
What Are Kids Learning?
- Evaporation is when a liquid changes into a gas. Liquid water evaporates to become a gas called water vapor.
- The sun's heat helps water evaporate and return to the atmosphere. There, it turns from water vapor back into liquid water and forms a cloud. Eventually, this water may return to Earth as rain or snow.
- In the water cycle, water moves from the land, lakes, and oceans to the atmosphere and back again.
How Do You Get Ready?
- Read the activity and gather the materials
- Scout out paved places where this activity will work well, such as a playground, a parking area, or a sidewalk.
- If feasible, bring a few pails of water outdoors before kids arrive.
- Cut 8 x 11" pieces of construction paper into 4 pieces.
Warm-up 5 minutes
Engage kids in a conversation about water in their daily lives.
- What happens to our neighborhood or schoolyard when it rains?
- What happens to the water after the rain stops and the sun comes out?
- Where do you think the water goes? Does it just disappear? How could we find out?Some soaks into the ground, and some evaporates into the air. We could find out where it goes by pouring water on the pavement and sealing the wet area with a piece of plastic. We could also pour water on the ground and dig a hole to see how far the water goes into the ground.
Explain that, next, you'll explore evaporation in action in your schoolyard and compare how factors like sun and shade affect how quickly water evaporates.
Activity 40 minutes
Part A Paint with Water
Give each pair of kids a pail of water, paintbrushes, and chalk. Head outdoors and have them:
- dip a brush into the water and paint a picture on the pavement in the sun.
- sketch the painting in their field notebooks.
- predict what will happen to the painting in five minutes.
Have kids repeat the steps above, but this time have them paint:
- the same thing on a wall of your building.
- the same thing on the pavement in the shade.
- the same thing on the pavement in the shade, but this time, blow on the painting, or fan it with a piece of paper.
While groups are painting, circulate among them.
- What do you see?
- What's happening to the water?
- Is it all soaking into the pavement or the wall, or is some evaporating?
- How can you tell?
- What will your painting look like in 10 minutes? Half an hour?
Then, ask if they might like to see some evidence of water evaporating.
Part B Disappearing Handprints
- Next, give each pair of kids 4 pieces of construction paper and 2 sandwich bags.
- Have kids dip their hands in the water, shake off the excess, and make a handprint on each piece of construction paper.
Have the kids each place one of their handprints in a sandwich bag and seal it up, leaving enough air inside so the top of the bag does not touch the paper. They should leave the other handprint on the ground, uncovered. Have them make a prediction.
- What do the handprints look like now?
- What will happen to the handprint in the bag?
- What will happen to the other handprint?
Have kids sketch the handprints and jot down their predictions in their field notebooks.
Part C Where Did the Water Go?
When kids have finished setting up their handprints, have them look at their water paintings.
- Have the paintings changed? How?
- Compare the painting in the sun to the one in the shade. How are they different?
- How about the painting on the wall?
Have them jot down their responses in their field notebooks, using complete sentences.
Finally, have kids look one last time at their handprints.
- What happened to the handprints?
- Can you think of an explanation for what you see?Water doesn't vanish into thin air. When it evaporates, it forms tiny droplets called water vapor. Eventually, these droplets collect into larger droplets that we can see. This is called condensation. In nature, these droplets form into clouds and, eventually, rain. In the experiment, the water in the handprints evaporated and then condensed into droplets on the surface of the bag.
Wrap-up 15 minutes
Quickly reconvene as a group–in front of a wall of your building, if you can. Write the word "EVAPORATE" on the wall using sidewalk chalk, or on a piece of poster paper.
- What happened to your water paintings?
- What differences did you see between paintings in the sun and in the shade?
- What happened to your handprints?
- What did you see inside the plastic bags?
- What does that tell you about where water goes when it evaporates?
Finally, tell kids that as a group, you are going to act out what happens to water on a sunny day.
- Crouch down and invite kids to do the same, telling them that you are all water molecules that just fell to the ground as rain. Now tell them the sun is coming out. Rise up and jump into the air, reaching up your hands, and shout "EVAPORATE!"
Explore Some More
Play with Puddles
If it has rained recently, grab some chalk and head out in search of puddles in the schoolyard, on a paved parking lot, or on the sidewalk.
Challenge kids to find:
- a puddle in the shade.
- a puddle in the sun.
- a puddle wider than their arms can reach.
- a puddle no bigger than their feet.
- a puddle deeper than their thumbnail.
- How will the puddles change if you come back in half an hour? Why?
- Which puddle will last the longest? Which one will evaporate first?
Return in half an hour to find out!
Give kids paintbrushes and cups of water. Have them paint a picture on the backs of their hands or on their forearms and then blow on it.
- What happens to the water?
- Does your hand feel any different?
Explain that when water evaporates, it takes heat with it. This is why your body feels cooler when you first come out of a bath or shower. As the water on your skin evaporates, it takes some of your body's heat with it.