Activity 3.2PT: Observing Plants’ Mass Changes, Part 1 (30 min)

Target Student Performance

Students harvest their radish plants and dry down the plants and the paper towel or gel in preparation for Activity 3.4.

Resources You Provide

Containers of radish plants from the Pre-Lesson (1 per group)
Digital scale (1 per group)
Small paper bags or envelopes for drying plants (1 per container)
Sunny windowsill or drying oven (domestic ovens work at low settings)
Markers to label plants by student or group (1 per group)

Resources Provided

Setup

Prepare your computer and projector for the 3.2PT Observing Plants’ Mass Changes, Part 1 PPT. Print one copy per student of the 3.2PT Observing Plants’ Mass Changes, Part 1 Worksheet.

Directions

1. Use the instructional model to show students where they are in the course of the unit.

Show slide 2 of the 3.2PT Observing Plants’ Mass Changes, Part 1 PPT.

2. Have students count and harvest the plants.

Follow the instructions in Part A of the 3.2PT Observing Plants’ Mass Changes, Part 1 Worksheet.

Show students slide 3 of the PPT and keep this up during the first part of the activity.

Students should count and record the number of germinated plants vs. non-germinated seeds.
Students should record the mass of their drying container (plants will stick when dry, so hard to separate) and label it.
Guide students through carefully pulling their radish plants out from the wet paper towel. Try to get all the plant material (even roots and non-germinated seeds) in the envelopes or paper bags.

3. Dry the plants.

Follow the instructions in Part B of the 3.2PT Observing Plants’ Mass Changes, Part 1 Worksheet.

Labeled envelopes containing plants and the containers with the wet paper towel can be placed on a windowsill to dry out or can be dried overnight at the lowest temperature in a home oven. (<170 degrees) IF YOU USE AN OVEN—make sure that the material you place the plants on will not burn and start a fire! Windowsill plants will take a few days to dry if small, but may take longer if they are large.

4. Have students record their observations

Record observations of the plants in Part C of 3.2PT Observing Plants’ Mass Changes, Part 1 Worksheet.

Show slide 4 of the PPT, which lists a few observation idea starters.

5. After drying the plants/gel, continue with Activity 3.4.

Since it may take several days for the plants to dry, there are options for what to do with your students while waiting. You may move on to Activity 3.3 and conduct the Light and Dark Investigation. Or, if you started with Activity 3.3 first, you may move on to Lesson 4 which focuses on following up results from the Light and Dark Investigation (Activity 3.3) with explanations of photosynthesis and cellular respiration. Later, students will complete Evidence-Based Arguments for this investigation (Activity 3.5) and Explanations of biosynthesis in plants (Activities 5.1, 5.2, and 5.3). See the Plants Unit Front Matter for more information about this decision.

Assessment

Since this activity is primarily an opportunity for students to harvest their plants for Activity 3.4, there is little content in this activity to assess. You can use 3.2PT Grading Observing Plants’ Mass Changes, Part 1 Worksheet to grade your students’ work in collecting observations on 3.2PT Observing Plants’ Mass Changes, Part 1 Worksheet.