Italicized font represents information to be shared orally or physically completed with the students at this time.

The non-italicized font represents additional information included to support the teacher’s understanding of the content being introduced within the CELL.

ASK WHY

Remind students that plants are all around us. We tend to take them for granted, but imagine a world without lush green grasses and trees – a planet blanketed in desert. Could we survive? Plants are an integral part of our environment and provide the food, oxygen, and fibers we depend on for survival. And their ability to photosynthesize is one of nature’s most amazing and essential phenomenons.

BRANCH OUT

Remind students that horticulturists improve crop yield, quality, nutritional value, and resistance to insects, diseases, and environmental stresses. They make plants more adaptable to different climates and soils and better fit for food uses or processes. They also grow and improve plants used for medicines or spices.

GET FOCUSED

GO DEEPER

As a class, read the Background(s) in the Investigation. Have students read the information aloud or silently to themselves. When students have finished, discuss the following concepts as a class:

• Photosynthesis is a process carried out by some bacteria, algae, and plants.
• During this process, energy from light is converted into the energy of chemical bonds.
• Photosynthesis reduces carbon dioxide to three carbon sugars and oxidizes water to oxygen.
• The reactants in photosynthesis reaction are carbon dioxide gas, CO2, and water, H2O.
• The products are oxygen gas, O2, and sugar molecules.
• In the chemical equation, the reactants are found on the left side of the yield arrow. The products of the reaction are found on the right side.

• To observe the levels of carbon dioxide during photosynthesis, a pH indicator called phenol red can be used.
• Phenol red is red in a basic solution and yellow in an acidic solution.
• Carbon dioxide makes a solution more acidic, or more towards the yellow and orange colors when using phenol red.
• When the carbon dioxide in a solution is used, the carbon dioxide level decreases. The solution then becomes more basic, or more towards the red or purple colors when using phenol red.

Note: These concepts are integrated into the Background(s) and are used to deepen students’ comprehension of the big ideas.

LEARN THE LabLearner LINGO

The following list includes Key Terms that the teacher should introduce, as appropriate, within the CELL. These terms should be used, as appropriate, by teachers and students during everyday classroom discourse.

• pH 

Note: A definition of this term can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.

SET FOR SUCCESS

• Tell students that they will continue to investigate photosynthesis by observing carbon dioxide and oxygen quantities in water containing Elodea plants.
• Play the video below. Stop to ask students questions or answer students’ questions when necessary. Remind students to follow along with their SDRs and make any notes that they think might be helpful.
• After the video, direct students to divide into their lab groups to discuss their strategy for the lab. For example, they may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow students to anticipate the laboratory experience they will soon encounter. Students should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.

HOMEWORK

Tell students that they should review the Investigation in preparation for the Lab.