The Water Cycle

Unit Review Sheet

Facts and Definitions

Lesson 1: Water, Water Everywhere

• A water molecule is made up of two hydrogen atoms and one oxygen atom.
• Water absorbs heat, dissolves solids, and is transparent.
• Water molecules are attracted to one another.

Lesson 2: Clouds

• Clouds are made of tiny droplets of water or ice crystals.
• Stratus, cumulus, cirrus, cumulonimbus, and nimbostratus are types of clouds.

Lesson 3: The Water Cycle

• Water can exist in three states: solid, liquid, and gas.
• Water never leaves Earth's atmosphere, so the same water has always been on Earth.

Lesson 4: Water Cycle Processes

• Evaporation is when the Sun heats water and the water moves from the surface of the Earth into the atmosphere.
• Transpiration is the process by which the Sun heats plants, and water enters the air through tiny holes in leaves.
• Condensation occurs when water vapor forms tiny droplets of water that float in the sky and become clouds.
• Precipitation occurs when the water droplets in clouds become too heavy to stay in the sky and fall to the ground in the form of rain, snow, hail, or sleet.

Lesson 5: Animals and the Water Cycle

• Some animals can live only in fresh water and some can live only in salt water.
• All animals and plants are dependent on the water cycle.

Final Project: The Water Cycle

• [none]