Authentic Lessons for 21st Century Learning

You Are My Sunshine

Photosynthesis

K20 Center, Alexandra Parsons, Lindsey Link, Brittany Bowens | Published: June 9th, 2022 by K20 Center

Summary

In this lesson, students explore energy conservation based on how energy from the sun is captured and used to make chemical energy. Students also review how solar energy and the concept of photosynthesis have been used to engineer technology that could be beneficial to humans. This lesson can be used to introduce or conclude a photosynthesis unit.

Essential Question(s)

How does energy guide function?

Snapshot

Engage

Students watch solar dancing toys and record their observations.

Explore

Students conduct a lab with spinach and light.

Explain

Students answer questions about the lab.

Extend

Students read about photosynthesis and renewable energy.

Evaluate

Students create two-minute documentaries about the articles they read.

Objectives

  • Determine how organisms capture and store free energy from physical sources (the sun) for use in biological processes (photosynthesis). 

  • Evaluate the contributions of photosynthesis and the capturing of light in the creation of man-made technology.

  • Construct explanations based on scientific evidence as to how the interaction of subcellular structures provides essential function.

  • Investigate the best pigment for light absorption and its level of efficiency for photosynthesis.

Materials

Entire Lesson

  • Lesson Slides (attached)

  • Carbon Is Not the Enemy (attached)

  • Reverse Photosynthesis Uses Sunlight to Convert Plant Biomass Into Fuel (attached)

  • The Difference Between Photosynthesis and Solar Cells (attached)

  • Why the Secret of Blue Begonias Can Improve Energy Efficiency (attached)

  • Solar dancing toys (3)

Explore (Option 1)

  • Photosynthesis Lab (attached; 1 copy per student)

  • Timer (1 per group)

  • Light lamps (4–5)

  • Spinach leaves (3–5 per group)

  • Hole punch (1–2 per group)

  • Clear cups or beakers (2 per group)

  • Large syringe without needle (2 per group)

  • Baking soda (1.5 g per group)

  • Liquid dish soap (1 bottle)

  • Water (600 mL per group)

Explore (Option 2)

  • P51™ Chlorophyll Lab: Green Glows Red! (linked here and in the narrative; 1 copy per student)

  • Spinach leaves (3–5 per group)

  • Acetone or 90%+ isopropyl alcohol (about 2 ml per group; volume depends on the extraction method)

  • 70% isopropyl alcohol (~0.5 cm-deep covering of chromatography chamber per group)

  • Filter paper for chromatography (1 per group)

  • Mortar and pestle (1 per group)

  • Paper chromatography setup: beaker and glass stirring rod, or similar (1 per group)

  • Pipettes (micropipettes or plastic transfer pipettes can be used) (1 P20 or P200 with tips, or several plastic transfer pipettes, per group)

  • Funnel and filter paper, or microcentrifuge (1 per group)

  • 200 µl tubes (about 5 per group)

  • 1.7 ml microcentrifuge tubes (if using a centrifuge) (1–3 per group)

  • P51™ Molecular Fluorescence Viewer or other blue light illumination system (1 per group)

  • Gyro™ microcentrifuge, fixed speed

  • 10 µl micropipette tips (2 racks of 96)

  • 10 µl minipette (fixed volume micropipette; set of 10)

  • 200 micropipette tips (2 racks of 96)

  • 20–200 µl adjustable volume micropipette (H-style)

  • 4 µl minipette (fixed volume micropipette; set of 10)

  • Set of 4 adjustable-volume micropipettes with rack: 0.5–10 µl, 2–20 µl, 20–200 µl, and 100–1,000 µl (H-style)

  • Disposable lab pack: 50 slides, 50 plastic cover slips, and lens paper booklet

Engage

5 Minute(s)

As students enter the classroom, allow them the freedom and time to watch the solar dancing toys or whatever students want to do. After a minute, introduce the lesson using the attached Lesson Slides. Display slide 3 to read aloud the essential question. Display slide 4 to go over the lesson objectives. Review these slides with students to the extent you feel necessary.

Bring students’ attention back to the solar dancing toys. Display slide 5 and ask students: "Why is this happening?"

In response to that question, have students write a statement of speculation as to what is happening with the toys. Then, have each student share their explanation with a partner.

Students are going to revisit both the question and their original statements at the end of the lesson, so have students store their responses for later.

Explore (Option 1)

40 Minute(s)

The Explore section of this lesson has two lab options for you to choose from. Option 1 focuses on the reactants necessary for photosynthesis and the products of this process.

Display slide 6 and pass out a copy of the attached Photosynthesis Lab handout to each student. Allow students to form groups and ask them to answer the three pre-lab questions on the handout.

Once students have answered the pre-lab questions, have them read through the lab procedure and instructions before beginning. Be sure to answer any questions that arise as students work, and remind them to record the data they collect on their lab handouts.

After students have completed the lab, have them answer the post-lab questions on the handout.

Explore (Option 2)

45 Minute(s)

The Explore section of this lesson has two lab options for you to choose from. Option 2 focuses on how light is captured, identifies the structural components that capture light, and reviews the effects of light wavelength on the rate of photosynthesis.

Display slide 6 and pass out a copy of the P51 Chlorophyll Lab: Green Glows Red! to each student. Read the instructions aloud to review expectations as a class.

Organize students into groups of 3–4 and have them work through the lab together. Be sure to answer any questions that arise as students work, and remind them to record the data they collect on their lab printouts.

After students have completed the lab, have them use the Claim, Evidence, Reasoning (CER) strategy to record their observations of chromatography during the lab and answer the analysis questions.

Explain

15 Minute(s)

Once students have finished the lab, help them come up with the equation of photosynthesis based on what they discovered in the lab. As students share out, write what they say on the board and guide them to this equation:

6 CO2 + 6 H2O –> C6H12O6 + 6 O2

Display slide 7 to reveal a diagram of photosynthesis within the chloroplast. Have students closely examine the diagram so they can understand the full complexity of light-dependent and light-independent (Calvin Cycle) reactions.

Go to slide 8 and ask students to consider the reaction for photosynthesis and how it relates to their lab data. As the first part of a Think-Pair-Share activity, have students write their answers to the following questions:

  • In the lab, where did the carbon dioxide come from?

  • What role did the light play? What did the light do?

  • What did you observe that let you know photosynthesis was occurring? How does that fit into the equation?

  • In the water solution, do you think the leaf disks were still making sugar? Why or why not?

After students have written their answers, have them pair up and share what they wrote with their partners.

Once students have confidence in their answers, call on several pairs to share their speculations with the whole class.

Extend

15 Minute(s)

Organize students into five groups. Give each group copies of one of the following attached articles:

  • Carbon Is Not the Enemy

  • Reverse Photosynthesis Uses Sunlight to Convert Plant Biomass Into Fuel

  • The Difference Between Photosynthesis and Solar Cells

  • Why the Secret of Blue Begonias Can Improve Energy Efficiency

Display slide 9 and explain the CUS and Discuss strategy to students. Ask them to do the following as they read their group’s assigned article:

  • Circle words or concepts they don't understand.

  • Underline details that support the main idea.

  • Star the main idea.

After students have finished, have them discuss what they marked and why with their group members.

Evaluate

50 Minute(s)

Once students have discussed their articles with their groups, go to slide 10. Inform students they are going to create Two-Minute Documentaries to present the information from their articles to the entire class.

Resources