Home >> Science & Nature >> Nature

Second Grade Science Experiments on Photosynthesis

For a second grader, plants may be difficult to understand as they have few of the same characteristics as humans. However, plants are essential to human life, and understanding plants is important to a student's understanding of the natural world. Plants, unlike humans, produce their own food using sunlight in a process called photosynthesis. There are many simple experiments that students can do to learn about photosynthesis.

Light
- Plants are able to make their own food. However, they must have a source of light in order to survive. Take two plants of the same species and same general size. Put one in a dark space, like a closet. Put the other in a sunny or well-lit area and give both the same amount of water. After a few days, take out both plants and examine them. The one that has been in a dark area may seem withered. Ask the students which one seems healthier and why they think they got these results.
Air
- Along with light, plants need air for photosynthesis. Essentially, they "breathe" and need air the way humans do, although they use and absorb air differently. Humans inhale oxygen and exhale carbon dioxide, and plants use carbon dioxide and release oxygen. Gas is exchanged through small openings in the leaves, called stomata. Smear a thin coat of petroleum jelly on a few leaves of a plant, which blocks the stomata. Wait for a day or two, then examine the leaves that were coated, comparing them to uncoated leaves. The coated leaves may seem withered compared to the uncoated leaves. Ask the students what they think happened to the leaves, then discuss how plants and animals need air to survive.
Color
- Second grade students are familiar with the colors and rainbows. Light is actually made from many colors, and only use some of the colors for photosynthesis. This is the reason that plants are green, although that concept may be difficult for second grade students. Take three similarly sized plants of the same species and put each under a differently colored light, one red, one blue, and one yellow. Wait for a week, then compare the plants. Ask the students which plants seem healthiest, and which colors they think are best for plants.
Temperature
- Plants survive best at certain temperatures, much like animals. The temperature affects the rate of photosynthesis as well, and photosynthesis works best at a certain temperature range. Plants that are at an optimal temperature grow better than ones that are not. Take several similarly sized plants of the same species and put them in different areas with similar lighting, but different temperatures, such as sunny or drafty places. You can build a miniature greenhouse to get a hot temperature, if desired. Let the plants grow for one or two weeks, then compare them. Ask the students which plant seems healthiest. Then ask the students to think about how different environments can be from one another; for instance, a camel's environment compared to that of a penguin. Do they think that the plant species is important to deciding what temperature it will grow best at?

Nature