1. Distribute the Tropism Twist activity sheet to each student. Ask students to write a hypothesis for the testable question, “Does light affect the direction that a seedling will grow?” in the appropriate place on their worksheet.
2. Divide students into lab groups consisting of 3-4 students. Distribute shoebox, scissors, duct tape, and cardboard. Instruct students to write their names on the bottom of the shoebox.
3. Show students a completed tropism testing box and guide them through the steps of creating their own boxes. Use the diagrams to guide students through the construction process.
   • Carefully draw and cut out a two-inch square from the middle section of one end of the box. Students may need help from the teacher and the teacher’s utility knife. It is recommended that only the teacher be equipped with a utility knife.
   • Place the lid on the front of the box. Hold the box up to the light. Look through your two-inch hole and make certain that this hole is the only source for light to get into the box. Carefully duct tape over any other cracks or crevices that may be letting light in. Do not tape the box shut.
   • Using paper to create a pattern, cut two pieces the height of the inside of the shoebox and half the width. Trace the pattern on stiff cardboard and cut them out. Tape them into the box as shown.
4. After tropism boxes are complete, instruct students to use the designated planting station to plant two bean seeds for their group experiment. The planting station should be supplied with newspaper, 6-ounce plastic cups, potting soil, bean seeds, water spray bottles, craft sticks, masking tape, and markers for labeling.
5. Place planted seeds in a lighted area and wait for the seeds to germinate. When the seedlings are approximately two inches tall, place the watered seedlings into the shoebox as shown.
6. Close the box, tape it, and place it by a sunny window so the square hole on the top can be exposed to the light.
7. After five days, carefully shine a flashlight through the square hole to observe the plant growth. It is best not to disturb plants during this testing period. It can alter the final outcome.
8. In another 3-5 days, check to see if the plant has grown enough to reach the top of the box. Remove the shoebox lid once the plant has reached the top of the shoebox. Have students record their observations and answer the questions on their Tropism Twist worksheet.

Variations

• Have students plant the bean seeds, then build the tropism boxes on another day while you are waiting for seeds to germinate.
• Using different kinds of seeds, test to see if different kinds of seedlings display phototropism more than others. Do some seedlings bend and twist the moment they germinate? Do other seedlings show no sign of phototropism? Compare and contrast growth rate and angle of growth rate between seedlings.