The Water Cycle — Answer Key
Part A: Fill in the Blank
Write the missing word on the line.
1. The sun heats water in oceans, lakes, and rivers.
The sun provides the heat energy that warms water in oceans, lakes, and rivers, starting the water cycle.
2. When liquid water is heated, it turns into water vapor.
When liquid water is heated by the sun, it turns into water vapor, which is water in the form of an invisible gas.
3. The process of water turning into water vapor is called evaporation.
Evaporation is the process where liquid water is heated and changes into water vapor that rises into the air.
4. Water vapor is water in the form of a gas.
Water vapor is water in the form of a gas that is invisible and lighter than liquid water.
5. Water vapor rises up into the sky because it is lighter than air.
Water vapor rises up into the sky because it is lighter than the surrounding air.
6. High in the sky, water vapor cools down and turns back into tiny water drops.
High in the sky the air is colder, so water vapor cools down and turns back into tiny water drops through condensation.
7. When water vapor turns into tiny water drops, it is called condensation.
Condensation is the process where water vapor cools and changes back into tiny liquid water drops.
8. Tiny water drops stick together in the sky to form clouds.
Tiny water drops stick together in the sky to form clouds, which grow larger as more vapor condenses.
9. You can see condensation on a cold glass of water when drops form on the outside.
Water drops form on the outside of a cold glass because warm water vapor in the air condenses on the cold surface.
Part B: Match the Water Cycle Stage
Draw a line from each water cycle stage to its description.
1.
Evaporation
→ The sun heats water and it becomes vapor
Water falls from clouds as rain or snow
Condensation
→ Water vapor cools and forms clouds
Water vapor cools and forms clouds
Precipitation
→ Water falls from clouds as rain or snow
Water gathers in rivers, lakes, and oceans
Collection
→ Water gathers in rivers, lakes, and oceans
The sun heats water and it becomes vapor
Evaporation → The sun heats water and it becomes vapor because heat changes liquid water to gas. Condensation → Water vapor cools and forms clouds because cool air turns vapor back into drops. Precipitation → Water falls from clouds as rain or snow when clouds become too heavy. Collection → Water gathers in rivers, lakes, and oceans where it waits to be heated again.