PLANTS AND SUNLIGHT

 

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LEVEL:  Elementary

 

CONCEPT:  Biological Science – Plant Needs – Sunlight

 

OBJECITVES:  The Student will be able to prove that a plant needs light in order for it to develop correctly.

 

MATERIALS:  Sunflower seeds (any alternative seed will do), potting soil, flower pots of plastic containers, box, aluminum foil, houseplant, two plants the same size

 

BACKGROUND INFORMATION:  Plants need food and can make their own food.  But they need things from which to make their food. Green plants need carbon dioxide from the air, water, and minerals from the soil, and energy from the sun.

 

Only in light can a green plant make food.  The process of food making is called photosynthesis.  In photosynthesis, the carbon dioxide and water are changed to carbohydrates and oxygen.  Food can only be made in the presence of chlorophyll.  Chlorophyll is the substance responsible for a plant’s green color.

 

When a green plant is deprived of sunlight, it soon loses its chlorophyll.  It cannot make food, so it dies.

 

PROCEDURE: 

  1. Soak the sunflower seeds overnight.  Then plant three sunflower seeds in each pot and put them near the window.   Water the pots well.  Now cover one pot with the cardboard box.
  2. When the first true leaves appear on the plants that are uncovered, remove the box from the other pot.
  3. Discuss with the students what happened to the plants.  Why did the sunflower seed under the box not grow?  Do plants need light to grow?  Do they need light to remain healthy?
  4. When a plant gets no sunlight, it cannot make food. Without food the plant will die.  Use two plants of the same size. Cover one with a box or place it in a closet to block the sunlight.   The plant that did not receive sunlight will lose some of is green color.  It will not look as healthy as the other plant.  Make sure it now receives sun and watch for it to return to health.

 

EXTENSIONS:

  1. Put a potato in a dark, warm spot for several weeks.  What happens to the potato?  If left in the dark for several months, will the potato die?  Try it.
  2. Lay three of four seeds in the bottom of a shallow bowl and place a wet sponge over them, Keep them damp.  When the seeds sprout, watch to see what happens to them.  Turn the dish.  Do the seedlings turn toward the light?
  3. Put a rock or a board on a patch of grass, leave it for two weeks.  Take the rock off and observe.  What has happened to the grass?  Is it a different color from the surrounding grass?  Has the grass died?  Now leave he rock or board off the grass.  Does the green color return to the grass?
  4. Write a plant log about one of the experiments.
  5. Let the students make up an activity of their own with plants and sunshine.

 

 

TECHNOLOGY:  Have the students keep their plant long using a word processing sheet or have them create a chart in excel to fill in daily.

 

 

Adapted from 1990 Aims Education Foundation