Transpiration lab

In this activity, your students will observe the process of transpiration. They will determine the rate of transpiration for one plant branch.

A lesson plan for grades 9–12 Science

By Sadie Buie, James Caldwell, Jeanette Fredericks, Janice Shue, Katie Wadsworth, and Tracy Watson

About the authors

I teach AP Biology and Honors Biology II at Chapel Hill High School.

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• Transpiration An overview of transpiration

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Learning outcomes

Students will:

1. Collect and record data
2. Use data to answer questions
3. Observe transpiration

In this activity, your students will observe the process of transpiration. They will determine the rate of transpiration for one plant branch.

Teacher planning

Time required for lesson

2 days

Materials/resources

Materials:

• a bean, or other plant, branch/stem
• scissors
• ruler
• two test tubes (same size)
• test tube rack
• clock
• graph paper
• water
• glass marking pencil

Pre-activities

Students should understand transpiration.

Activities

Teacher hints:

1. You can cut stems of plants yourself. However, if you use grown plants, you must plant the seeds (I use beans) two to three weeks prior to the lab activity.
2. Make all measurements in millimeters.
3. You may want to remind students of controlled lab setups to help with the question about the test tube in which evaporation occurs.
4. Review the concept of slope to determine rate.
5. Cut the plants with scissors and place them quickly into the test tube.

Student procedures:

Day One:

1. Obtain two test tubes. Fill each test tube three-quarters full with water. Place both test tubes in a test tube rack.
2. Follow the teacher’s instructions to obtain your plant stem.
3. Place the plant stem so that it stands upright in one of your test tubes. Use the lab sheet to continue with activity.
4. Use the glass marking pencil to mark the water level in each of the test tubes.
5. Use a ruler to measure the height of the water in each test tube. Record these initial amounts in the lab table.
6. Check the water height every ten minutes. Record the height of the water in each tube until the end of class.
7. Follow the teacher’s instructions for clean up and where to place lab set up overnight.

Day Two:

1. Obtain the lab set up.
2. Measure the height of water in each tube. Record height of each in the lab sheet from yesterday.
3. Follow the teacher’s instructions for final clean up of material.
4. Graph your results.
5. Answer the lab questions. (Answers)
6. Determine the rate of transpiration.

Assessment

I usually give points for the following:

• ten points for the table
• twenty points for the graph (two lines)
• ten points for the rate of transpiration
• ten points for the lab questions

Supplemental information

Comments

A great and simple lab that allows students to see transpiration.