Kids’ Experiments with Color, Light & Plants

Experimenting with light wave lengths, color and plants can be an interesting way to teach children basic scientific concepts. The pigmentation of plants, the amount and quality of light it receives and even the type of plants growing nearby can all have an impact on the experiment. This will also help teach children the concept of a “hypothesis” and show them why a hypothesis is not the same as a fact.

Chlorophyll and Photosynthesis
Chlorophyll is what gives plants their green coloring but it is also a molecule that absorbs sunlight. In other words, chlorophyll is what makes photosynthesis –or the plants ability to make energy from sunlight– possible.

One way of experimenting with chlorophyll is to control the color of the light the plant has access to. Use colored cellophane to wrap up the plant or you could use a green house with colored window panes. The light spectrum contains every color in nature so you can use just about any color for your experiment although blue, green, red and white light are the most commonly used. To achieve visible results you should only use one color on each plant and have a “control” plant (one grown without colored glass or cellophane) to compare your results to. Your plants should all be of the same type and about the same size before starting the experiment.

Effects of Lighting on Plants
Sunlight gives off both UVA and UVB rays of light, both of which plants need in order to grow. UV refers to “ultra violet,” so called because violet has the shortest wavelength of light. Ultraviolet means that the lights wave length is even shorter than that of violet light. UVA is an ultraviolet wave with a long range while UVB has a mid-range reach.

Experiment with lighting by placing a number of plants of the same type in different lighting situations and measuring the growth after a certain time frame. For example, use a fluorescent light, a black light, normal sun light, an incandescent light bulb and a light made specifically for plant growing. Each of these lights give off varying degrees of UVA and UVB rays. Place each plant in a dark room with a light (except for one plant placed in sunlight) and turn the light on for the same number of hours as the plant in the sun gets of light each day.

Harnessing the Power of Pigmentation
Many plants use their coloring to repel or attract a variety of insects, some beneficial and some damaging. Many of these plants also use odoriferous chemicals in combination with the pigmentation but the coloring alone can have surprising effects. Look up pictures of different kinds of plant camouflage, some used in plants that attract bug and some in those that repel them. Make a cloth that mimics the patterns of these plants and wrap it around a plant with no bugs on it. Observe the plants (including a control plant) over the next few days and note if and how insects are now reacting to it. Reactions can include insect damage such as eaten leaves, sudden infestation or a complete absence of bugs where there used to be many.

Create an Artificial Autumn
Trees change color in the fall due to a lessening of chlorophyll caused by reduced sunlight. Use a small potted tree with many leaves for this experiment. Over the space of a few weeks slowly supply the tree with less and less time in sunlight until it is only getting one or two hours a day. You can also use a sunlamp instead of placing the plant in sunlight. This will give you complete control of the quantity and quality of light the plant receives. Make a hypothesis based on three possible outcomes: no change, leaves change colors, leaves fall of without changing color.


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