Teaching Elementary Science: Photosynthesis

Autumn brings changes in the colors of the leaves. This is the perfect time to introduce students to the concept of photosynthesis, the process where plants make their own food. Photosynthesis doesn't have to be as hard as it sounds. This interactive lesson plan on photosynthesis is geared toward elementary students and can easily be adapted to most grade levels.

Objective:
Students will be able to describe the process of photosynthesis.

Time Frame:
Two 50-minute class periods.

Materials:
-pictures of leaves turning colors (See link in introduction.)
-8 cardstock pieces hung on yarn (Write these terms on the cards in magic marker: sun, plant, water, carbon dioxide, energy, oxygen, sugar, narrator.)
-Clay, enough for each group: white, brown, yellow, red, green are good colors (If clay is not available, use colored pencils and paper.)
-paper and pencil for each student
-index cards; 2 per group, precut into strips

Introduction:
Ask the students if they notice any changes in the neighborhood trees in the fall. Someone will respond that the leaves change colors. Show students pictures of what colorful trees look like in different parts of the country in autumn (click here for pictures from the U.S. National Arboretum website.)

Inform students that leaves actually have orange and yellow colorings, even during the summer. But the green color in the leaves is much stronger than the other colors, so it overpowers them. The pigment that gives leaves their green color is called "chlorophyll". When days get shorter and colder, leaves don't produce as much chlorophyll, so we start to see the other colors shine through.

The process that gives life to trees and plants is called "photosynthesis." Since photosyntheses requires lots of light and water--and there's not as much of those elements during the colder months--trees take "naps" until spring.

Today we're going to learn how photosynthesis (which means "putting together with light") works.

Procedure:

1. Explain the process of photosynthesis to students in simple terms. Draw a picture of this process on an overhead projection as you describe it (click here for a diagram.)

Plants draw water from their roots. Carbon dioxide is a gas in the air. It enters a plant through tiny holes in the leaves. This water and carbon dioxide is combined with energy from the sun. The sun helps to convert the water and carbon dioxide into sugar and oxygen. There is a green color in the plant's leaves called chlorophyll that allows plants to absorb the sunlight. It's the key in photosynthesis. If the plant has any leftover oxygen, it puts it into the air for us to breathe. Sugar that it doesn't use is stored in the plant. We often get fruits and vegetables from this energy.

2. Ask students to look at the picture you've drawn. Ask for different volunteers to explain photosynthesis in their own words.

3. Solicit 8 volunteers to act out photosynthesis (7 if the teacher is the narrator.) Distribute 8 large cards for the students to hang around their necks. They should be printed with "sun, plant, water, carbon dioxide, energy, oxygen, sugar, and narrator."

The "sun" stands up a little higher than others, possibly standing on a chair, waving his arms toward the plant to show energy.
The "plant" sits on a chair.
"Energy, carbon dioxide and water" circle the plant for a while and then sit down.
"Sugar and oxygen" then jump up.
The narrator explains the process in his own words as the students act it out. It's best for the teacher to narrate the first time.
Allow other groups of students to role-play photosynthesis.

Day 2:
Discuss what was learned about photosynthesis the previous day.
Divide students into groups.
Instruct each group to create a clay model of what happens during photosynthesis.
They should label the parts with index cards (place the words water, sun, carbon dioxide, oxygen, energy, sugar, plant on the board for reference.) If clay is not available, the groups can draw diagrams of photosynthesis.
Have each group explain their creations as you circulate.

Students who finish early could play the photosynthesis game if you have computer access.

Assessment:
Informal assessment will occur as the teacher observes the groups' clay creations of photosynthesis while simultaneously interacting and questioning students.
Students go back to their seats to individually draw sketches of what occurs during photosynthesis.

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Source: Education World