This lesson is appropriate for children ages 11 and up.

This lesson allows students to concretely experience the photosynthesis reaction by building models of the reactants and products with LEGO® bricks. 

The topic of photosynthesis is a fundamental concept in biology, chemistry, and earth science. Educational studies have found that despite classroom presentations, most students retain their naïve idea that a plant’s mass is mostly derived from the soil, and not from the air. To call students’ attention to this misconception, at the beginning of this lesson we will provide a surprising experimental result so that students will confront their mental mistake. Next, we will help students better envision photosynthesis by modeling where the atoms come from in this important process that produces food for the planet. Using models, students will utilize the atoms from carbon dioxide to build glucose. Additionally there is a follow-up activity where the students can build both cellulose and starch from the same glucose molecules to demonstrate how glucose becomes incorporated into the roots, shoots and wood—the structures of the plants we see around us! 

As a prerequisite, students need an introductory lesson on photosynthesis, something that includes the overall chemical equation. If students have already studied the intracellular photosynthetic process in detail, this lesson can still be very helpful because students often miss the big picture about photosynthesis.

Student Worksheets:

• Photosynthesis Student Pages Color
• Photosynthesis Student Pages B&W
• Photosynthesis Student Key

LEGO Materials:

• Atom Key Layout Mat
• Card A: Making Glucose Molecules
• Card B: Making Starch Molecules
• Card C: Making Cellulose Molecules
• Layout Mat for Glucose Parts and Glucose Check Mat
• Photosynthesis Reaction Mat Original​ OR Photosynthesis Reaction Mat White
• Poster: Plants Cells and Molecules 8.5 x 11
• Poster: Plants from Thin Air 8.5 x 11
• Atoms and Molecules Kits

Each kit contains the following LEGO bricks: 4 brown 2x4, 8 pink 2x4, 8 yellow 2x4, 8 light green 2x4, 8 green 2x4, 12 black 2x4, 36 red 2x4, 32 blue 2x4, 24 white 1x2. In addition, about 20 connector pegs are needed for the optional activity that builds cellulose molecules.

The  Atom Key Layout Mat shows the LEGO bricks we recommend for this lesson and the chemical reactions lesson. We chose these bricks because they can be used to illustrate a number of chemical and biological concepts. Their colors match those commonly used in other chemical models. The layout mat can also be used as an easy clean up tool to check if students have all of their bricks.

LEGO bricks can be purchased from the LEGO website, the Bricklink website, or at your local LEGO store. You might also arrange a LEGO brick donation with your local Parent Teacher Association.

We are currently creating a new teacher's guide. In the meantime, you may like to use this older version of LEGO Education's Teacher's guide:

• LEGO Education Photosynthesis Teacher's Guide
• LEGO Education Teacher's Guide Transparencies
• LEGO Education Student Worksheets

An interactive video called "Roots, Shoots, and Wood," with Dr. Kathleen Vandiver (inventor of this lesson), and produced by BLOSSOMS can assist you in teaching this lesson. A teacher's guide, written transcript, and class handouts can be found here. BLOSSOMS (Blended Learning Open Source Science or Math Studies) is a collaborative initiative seeking to begin to develop a large, free repository of video modules for high school math and science classes created by gifted volunteer teachers from around the world, seeded initially by MIT faculty members and by partnering educators in Jordan and Pakistan.

Video instructions to build the glucose molecule are on the MIT Edgerton Center YouTube Channel: "Making Glucose Molecules."

This lesson meets the following item of the Massachusetts State Frameworks for grades 6-8, Life Sciences (Biology) Strand.

16. Recognize that producers (plants that contain chlorophyll) use the energy from sunlight to make sugars from carbon dioxide and water through a process called photosynthesis. This food can be used immediately, stored for later use, or used by other organisms.

It also meets the following AAAS benchmarks:

4c, grades 9-12, Processes That Shape the Earth: Plants alter the earth's atmosphere by removing carbon dioxide from it, using the carbon to make sugars, and releasing oxygen. This process is responsible for the oxygen content of the air.

5E, grades 6-8, Flow of Matter and Energy: Food provides the fuel and the building material for all organisms. Plants use the energy from light to make sugars from carbon dioxide and water. This food can be used immediately or stored for later use. Organisms that eat plants break down the plant structures to produce the materials and energy they need to survive. Energy can change from one form to another in living things. Animals get energy from oxidizing their food, releasing some of its energy as heat. Almost all food energy comes originally from sunlight.

And it meets the following National Science Foundation Content Standard:

Content Standard C, grades 5-8: For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis. That energy then passes from organism to organism in food webs.