Teaching children about photosynthesis is not as intimidating as it may seem. When you break down the word, photosynthesis means "putting together with light." In photosynthesis, plants use the energy of the sun, water and carbon dioxide from the air to make their own food, which they use to grow. In the process, they release oxygen, which is part of the air we breathe in, as well as sugar, which is the plant's food.
Plants capture light from the sun inside parts of them called chloroplasts. When the sun shines on the leaves of plants, it goes into the chloroplasts. Chloroplasts are like solar panels because they observe and store sunlight. It is inside the chloroplasts where photosynthesis takes place. Chlorophyll is inside the chloroplasts. This chemical converts the stored sunlight during photosynthesis.
Chlorophyll has four different parts: one each that deals with water, carbon dioxide, oxygen and glucose, which is sugar. The light, water and carbon dioxide have a chemical reaction, resulting in oxygen and glucose. The oxygen and glucose are responsible for the creation of ATP, or adenosine triphosphate. ATP helps store the energy in the cells.
As soon as ATP has been created to store energy, plants begin light-independent reaction. This is in contrast to the light-dependent reaction described in previous sections, so called because sunlight is required to trigger the chemical reaction. Plants take carbon dioxide from water or air and mix it with water to create carbohydrates. Besides producing carbohydrates, plants use the ATP and carbon dioxide to create glucose, or sugar. This procedure of turning ATP into glucose is called the Calvin Cycle. Oxygen is emitted as a byproduct.
Methods of Teaching Photosynthesis
To help kids understand photosynthesis, make parallels between humans and plants. Have students brainstorm a list of food humans eat. Then make a list of what plants use for food based on what you've explained about photosynthesis so far. This list should include light, water and carbon dioxide.
Have your students make recipe cards using traditional index cards for plant food. They should list the ingredients and draw how the plant takes in and processes each ingredient. For example, the sun provides the light, rain provides water and air provides the carbon dioxide.
Do classroom experiments involving the photosynthesis process. Tape foil on a few leaves of a plant so they cannot absorb sunlight. After ten days or so, remove the foil and observe what happened to the leaves; they have turned dark and hardened because they could not receive light or water required for photosynthesis. In effect, they have starved because they haven't been able to produce food for themselves.