Investigating the Water Cycle: Using Plants to Study Evaporation
Initial Publication Date: October 5, 2007
Summary
In this science activity, students investigate the water cycle by testing the water evaporated from leaves (transpiration). They investigate concepts of evaporation and the movement of water through the different states of the water cycle by various guided inquiry experiments. Students compare evaporation of trees in the shade and in the sun. Students are asked to diagram their results for the experiment in their lab notebooks. Students are also asked to develop a testable question related to and formulate a method to evaluate their results. During another investigation, with a spin of the spinner, students simulate the movement of water within the water cycle and track their results.
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Learning Goals
This activity is designed for students to develop skills to gather information and to analyze the data collected. Students use inquiry-based skills of observation and questioning to formulate conclusions based on the data.
Objectives/Concepts for Water Cycle Activity:
1) Students will be able to describe the movement of water within the water cycle.
2) Students will be able to identify the states of water as it moves through the water cycle.
Objectives/Concepts for the evaporation activity:
1)Students will be able to explain the process of water evaporating (transpiring) from the plant.
2)Describe the importance of plants in the water cycle.
Vocabulary:
*Water Cycle
*Condensation
*Ground Water
*Evaporation
*Precipitation
Objectives/Concepts for Water Cycle Activity:
1) Students will be able to describe the movement of water within the water cycle.
2) Students will be able to identify the states of water as it moves through the water cycle.
Objectives/Concepts for the evaporation activity:
1)Students will be able to explain the process of water evaporating (transpiring) from the plant.
2)Describe the importance of plants in the water cycle.
Vocabulary:
*Water Cycle
*Condensation
*Ground Water
*Evaporation
*Precipitation
Context for Use
This activity is best suited for grades 3-5, but could be modified for higher levels. The investigation can be done with an entire class and includes a short field experience combined with a classroom activity. The field experience portion needs to be done in the fall, when there are still leaves on the trees or in May/June. At least two lesson times would be needed for this activity, one to go through the water cycle and activity, and one to do the evaporation experiment. The only equipment necessary are the bags/ties for the transpiration, the water cycle spinners and science journals. These activities would be appropriately placed as introductory lessons on the water cycle. Students should not need prior knowledge of the concepts. This activity could be adapted to use indoors with classroom plants that may be sitting in a sunny window, although the field experience is recommended.
Description and Teaching Materials
Evaporation Field Experience:
Pair students and give each student clear plastic bag with tie. Go outside and have partners put the bag over plants and tie. Make sure there are some duplicate plants, some in shade and others in sun. Record plant type and location. Go back inside and begin the observation sheet in the journal. Have students formulate a testable question related to the experiment.
Later in the day retrieve the bags and observe, discuss, and complete the method through results and conclusion.
Water Cycle Activity:
Students will need the water cycle spinners and their science journals. They will need to be put together with a spinner, or students may use a paper clip as the spinner and their pencil as the base for the spinner. Students should work in pairs to trace the journey a water droplet might make during it's journey. Spinners are designed specially to have students land on one area more than another, just like a real droplet would stay put in certain stages of the water cycle. (Refer to p.161 Project Wet curriculum for more information). Students should record the number of times the spinner lands in each area, which can be used for a class discussion on the water cycle. Students may also make a bar graph of the class results in the different stages of the water cycle.
Water Cycle Spinner (Microsoft Word 39kB Oct5 07)
Water Cycle Assessment (Microsoft Word 41kB Oct5 07)
NASA Water Cycle Diagram
Pair students and give each student clear plastic bag with tie. Go outside and have partners put the bag over plants and tie. Make sure there are some duplicate plants, some in shade and others in sun. Record plant type and location. Go back inside and begin the observation sheet in the journal. Have students formulate a testable question related to the experiment.
Later in the day retrieve the bags and observe, discuss, and complete the method through results and conclusion.
Water Cycle Activity:
Students will need the water cycle spinners and their science journals. They will need to be put together with a spinner, or students may use a paper clip as the spinner and their pencil as the base for the spinner. Students should work in pairs to trace the journey a water droplet might make during it's journey. Spinners are designed specially to have students land on one area more than another, just like a real droplet would stay put in certain stages of the water cycle. (Refer to p.161 Project Wet curriculum for more information). Students should record the number of times the spinner lands in each area, which can be used for a class discussion on the water cycle. Students may also make a bar graph of the class results in the different stages of the water cycle.
Water Cycle Spinner (Microsoft Word 39kB Oct5 07)
Water Cycle Assessment (Microsoft Word 41kB Oct5 07)
NASA Water Cycle Diagram
Teaching Notes and Tips
The water cycle portion of this activity is adapted from the Project Wet curriculum lesson entitled, The Incredible Journey. Students physically move in that activity and use dice instead of spinners. The spinners I've created allow for less preparation for the teachers and modify movement. This allows for more time to actually record, discuss, and graph the classroom results.
A practical tip for the evaporation experiment is to limit how far students may go to place their bags on the plants. Also, it is important to tell students to not go too far into any woods that may have poisonous plants.
A practical tip for the evaporation experiment is to limit how far students may go to place their bags on the plants. Also, it is important to tell students to not go too far into any woods that may have poisonous plants.
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Assessment
There are two assessments that I have included with this activity. One is a multiple choice quiz on the elements of the water cycle. The other is a more open-ended journal entry that can be used as an assessment. Assessment of student science journal work such as diagrams, observations, testable questions, or graphs is optional.
Standards
4.I.A, I.B-scientific inquiry; III.B- the water cycle