Plants Lesson 3 Background Information

Three-dimensional Learning Progression

This lesson provides students with experiences to observe and to collect data which will support them in their next lesson when they construct their explanations about photosynthesis and cellular respiration. They will observe that plants “breathe” (i.e., exchange gases with air) differently in the light and in the dark.

This lesson includes two PEO (Predict-Explain-Observe) Inquiry Activity Sequences with the final E (Explain) occurring in the next two lessons. We will consistently focus on the idea that understanding carbon-transforming processes involves answering the Three Questions:

  • The Matter Movement Question: Where are molecules moving? (How do molecules move to the location of the chemical change? How do molecules move away from the location of chemical change?)
  • The Matter Change Question: How are atoms in molecules being rearranged into different molecules? (What molecules are carbon atoms in before and after the chemical change? What other molecules are involved?)
  • The Energy Change Question:
    What is happening to energy? (What forms of energy are involved? What energy transformations take place during the chemical change?)

The investigations in all units will make use of two essential tools:

  • Digital balances. Students can detect movement of atoms (the Matter Movement Question) by measuring differences in mass. This Activity will ask students to harvest their plants to prepare for future dry massing.
  • Bromothymol blue (BTB). This is a liquid indicator that changes from blue to yellow in response to high levels of CO2. Thus, changes in BTB can partially answer the Matter Change Question by detecting whether there is a chemical change that has CO2 as a reactant or product.
Content Boundaries and Extensions