Investigation Sequence

Title

Water Cycle

Written by:

Ben Schmitz and Lara Morrow                 Date

 

Focus Questions

What is the water cycle? What are the stages of the water cycle?

Concepts

Content: Earth, Physical, & Life

Water has many different states.

Cross cutting concepts

 

Science Practice

 

Personal, Social, Technology, Nature of Science, History

 

Background information

Water enters the water cycle upon evaporation. Evaporation occurs when increases in energy (from the sun) is great enough to turn water into water vapor. Water vapor is also added to the atmosphere by transpiration. Transpiration is the release of water by plants. Plants collect water through their roots and lose it as it evaporates into the atmosphere through small openings on the undersides of their leaves. When water vapor cools, it condenses. We can see the condensation of water in the form of clouds. We can also see condensation whenever water vapor comes in contact with cold air or cooler objects. Water vapor condenses when it reaches higher elevations because the air is cooler. When water returns to the Earth, it can be absorbed into the soil. This process is called percolation. Water will trickle through the tiny spaces between the soil particles. This water is called ground water. Ground water can move to lower elevations and depression through underground "rivers." Precipitation that falls on the ground or on the surface of bodies of water can once again evaporate, starting the water cycle over again. The water cycle is an essential part of the natural system and is vital to all living things. Without the continuous return of fresh water to the land, land plants and animals could not exist.

Activity Sequence

1. Transpiration
2. Condensation
3. Percolation
4. Absorption
5. Condensation development
6. A water cycle environment

Activity Descriptions

Activity 1. Transpiration
Materials: desktop lamp, two clear plastic cups, spinach with stem and leaves, index card, scissors, water
Student action: Students will observe that the leaves transpire water, and that air contains water.
Procedure: With scissors make a slit to the center of the index card. Fill one cup half way with water. Insert
The spinach through the slit in the index card with the leaves above the card, and place stem side
of spinach in water. Place other cup upside-down so that the spinach leaves are completely
enclosed in the cup. Place under lamp. In three to four minutes observe the water condensation
collecting on the inside of the top cup.

Activity 2. Condensation
Materials needed: five frozen water balloons, small coffee pot, paper towels
Student action: Students will observe that water changes from vapor to liquid when warm air touches a cold
object.
Procedure: After filling balloons with water freeze over night. Fill coffee pot with water about half way, let the
water heat at least two minutes before beginning experiment. Have students feel the balloon to
notice that it is cold. Have students set the balloon on the coffee pot. Wait three to four minutes,
and ask students to pick up the balloon to observe what is forming on it. While students are
waiting have them predict what they will see. Have students place the balloon over a paper towel
to observe the "rain" coming from the balloon.

Activity 3. Percolation
Materials: One 2 liter pop bottle, two clear plastic cups, small coffee filter, small pebbles, sand, dirt, water.
Student action: Students will observe how pebbles, dirt and sand act as a natural water filter for dirty water.
Procedure: Cut bottom off of pop bottle. Place coffees filter in the spout end of the bottle, and place this end in
a clear plastic cup. Pour pebbles in filter, followed by sand and dirt. Mix water and some of the
dirt in the cup. Pour the dirty water through the filter.

Activity 4. Absorption
Materials: clear plastic cup, blue or red food coloring, stalk of celery with leaves left on, water, paper towels, ruler
Student Action: Students will examine water absorption in a celery stalk.
Procedure: Mix a tablespoon of food coloring and water in a clear plastic cup. Cut celery stalk two
centimeters from bottom. Place celery with leafy side up in colored water. Every five minutes cut a
centimeter off of bottom of celery and display on the paper towel the row of small circles in the
celery outlined by the colored water.

Activity 5. Condensation development
Materials: 2-liter plastic bottle, warm water.
Activity: Fill the bottle three-fourths full of very warm water, quickly cap the bottle, gently squeeze and release the bottle. You should see a cloud. Squeeze to see how pressure affects clouds. If the bottle gets foggy shake the bottle to clear the fog. If you can’t see a cloud you may want to use a flashlight. You may also want to add some dust or smoke from a match. Try all these again with the bottle one-fourth filled with water.

Activity 6. A water cycle environment
Materials: Jar, plants, bottle cap or shell of water, soil, sand, small rocks.
Procedure: Put rocks in the bottom, next sand, then soil, plant plants, water and put the lid on. Put the jar in a sunny place and see how the water cycle works. To adjust the water add more or leave thelid off.

Dr. Robert Sweetland's notes