Activity 3.4PT: Observing Plants’ Mass Changes, Part 2 (45 min)

Remind students about when they harvested their radish plants in Lesson 3.2.

• Assure that students have their completed worksheets in front of them from Pre 0.2PT and 3.2PT.
• Pass out the worksheet for today.
• Have students follow part B of the worksheet to record their mass data.
• Remind students to subtract the mass of the empty envelope (or bag) in Part B.

Following the directions in Part C on the students’ worksheet, have students fill in the data table, showing slide 3 of the 3.4PT Observing Plants’ Mass Changes, Part 2 PPT

• Have students record their data on their worksheets and follow the rest of the instructions on the worksheet to fill in their data table.

Have students select a recorder to input their group’s results on the 3.4PT Observing Plants’ Mass Changes Class Results 11 x 17 Poster. Lead a discussion to help students compare results across groups and identify patterns in the data.

• Use Slide 4 of the PPT to guide students through data recording.
• Have students compare the dry mass change of the plant with the dry mass change of the paper towel.
• Show students slide 5 of the PPT. Have students discuss whether the patterns they observe in the class data match with their predictions.
• Discuss any outliers or unexplained data points.

Show students slide 6 from the PPT and ask them to compare their results to Ms. A’s class results.

• Ask students if they recognize similar patterns from their own data. Use the poster to compare. What similarities or differences do they notice? What patterns do they see?
• Probe student thinking with questions such as, Where did this mass come from? Did the mass come from the paper towel? What evidence do we have to build our conclusions?
• Use slide 7 to discuss the idea that they know from this investigation that the majority of the mass of the plant did not come from the paper towel, so the mass must come either from air or from water. An unknown question is, does water or air make up the mass of the dried plants? Students may have some ideas about where this mass came from. Tell students that you will discuss where this mass came from later in this Lesson.

Use slide 8 and Part D of the worksheet to help students describe the patterns they observed during the observation.

• Help students to recognize that the mass changes provide them with evidence that much of the plant’s mass is coming from a source other than the medium in which it is growing. However, this evidence does not show where this mass is coming from.

Ask students to retrieve their completed tools from the 3.1 Predictions and Planning Tool for Plant Investigations. Have them compare the predictions they made with the results of the investigation. Which predictions were correct? Which predictions were incorrect? What questions do they still need to answer?

• Tell students that they will use the data that they collected here to help them to be able to answer the Matter Movement Question.

Show slide 9 of the 3.4PT Observing Plants’ Mass Changes, Part 2 PPT.

• Conclusions: What did you observe during the investigation?
• Predictions: Why do you think the amount of mass the plants gained is different from the change in the paper towel’s mass?
• On a sheet of paper or a sticky note, have students individually answer the exit ticket questions. Depending on time, you may have students answer both questions, assign students to answer a particular question, or let students choose one question to answer. Collect and review the answers.

The conclusions question will provide you with information about what your students are taking away from the activity. Student answers to the conclusions question can be used on the Driving Questions Board (if you are using one). The predictions question allows students to begin thinking about the next activity and allows you to assess their current ideas as you prepare for the next activity. Student answers to the predictions question can be used as a lead into the next activity.