Activity: Water Cycle Column, by Andrew Feeney

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Overview

Students will make a model of the water cycle using 2-liter bottles. Students will be able to see evaporation, condensation, precipitation and percolation working right before their eyes.

Purpose and learning goals

Students should be able to describe the water cycle and see how the recycling of materials is important to all living things.

Prerequisite knowledge

Students should know and understand the basic steps of the water cycle before this activity.

Intended grade level

6 - 8

Time involved

Teacher preparation: 45 minutes, student time: 75 minutes

Alignment to standards and benchmarks (for entire unit)

Colorado State Science Standard: 3.2: Students know and understand interrelationships of matter and energy in living systems.

AAAS Benchmark: Students should know and be able to explain the recycling of materials by determining a pathway of a substance that is important for life.

Background information for the unit

Bottle Biology by Mrill Ingram (http://www.bottlebiology.org/)

Materials (per group of 2 - 3 students)

1. Three 2-liter bottles
2. Two bottle caps
3. 60-cm cotton string
4. One film canister
5. Scissors
6. Clear tape
7. Razor blade or exacto knife
8. One cup soil
9. Water
10. Ice
11. Small plants or plant seeds (optional)

Preparation

1. Label bottles 1, 2, & 3
2. Cut the top off bottle 1
3. Cut the bottoms off bottles 2 & 3
4. Poke a hole in one cap and place this cap on bottle 2
5. Put a loop of string through the hole so 5 cm hangs below the cap
6. Place the cap with no hole on bottle 3
7. Tie the remaining string around the neck of the bottle so one end hangs down about 7 cm
8. Place bottle 2 upside down into bottle 1
9. Place bottle 3 upside down into the top of bottle 2

Student sheets/guides

Create a sheet with the materials and procedure written out. Give the students an observation table and some questions to answer.

Procedure

• Soak both strings in water
• Add about 150 ml of water to bottle 1
• Fill bottle 2 with moist soil so it covers the loop of string (make sure the string does not touch the sides of the bottle)
• (Optional) Place small plants or plant seeds in the soil in bottle 2
• Place the film canister on top of the soil in bottle 2
• Place the string from bottle 3 into the film can
• Fill bottle 3 with ice water
• Record observations of the water cycle at work

Reflecting on the activity/ideas for assessment

This lab takes a while to prepare, but the end results are really neat! It would be nice to let this lab continue for several days to emphasize the recycling of the water in the system.

Key questions that may be asked with 'Look fors'

• Look for evidence of evaporation, condensation and precipitation. What do you see?
• How does the water cycle purify dirty water?
• What role do plants and soil have in the process?

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