Life Cycle - Plants (1B)
Pre Lab 

   
OBJECTIVES:
  • Growing two kinds of plants from seeds.
  • Comparing the differences and similarities as both plants grow.

VOCABULARY:

  • growth
  • seed
MATERIALS:
  • clear plastic cups
  • a support medium for the seeds (preferably moistened blotter paper wrapped around the inside of a glass, cotton, or sand)
  • bean seeds soaked overnight
  • corn seeds (The intent of soaking is to speed germination. It makes a definite difference with the beans, but does not affect corn as fast.)
  • eye dropper
  • hand lens

Students watch seeds germinate.

 

BACKGROUND:

Seeds are wonderful little incubators for new plants. It seems like seeds know which way should face the sun and which way the roots should grow. Children are amazed when they actually follow a seed germinating to watch the leaves and roots grow. However, this observational task requires patience and time. As the plants grow, it is very instructive for students to look at the sides of the glass to see the roots and leaves start to grow.

PROCEDURE:
  1. Plant the seeds between the blotter paper or cotton so that the seed pushes against the surface of the glass. Have the children plant some of the seeds upside down and others right side up. Place a little water on the bottom of the glass to keep the paper moist. Cover the top lightly with saran wrap to keep the cups moist. You may want to have the students place about 20-40 drops of water. Instruct them that they have to keep the cotton moist, but not soaking wet. 
          
  2. It will help the children to focus on what is actually happening if they are asked to answer a few questions as they observe the growth. The following are suggestions:
    1. What kind of seed begins growing first?
    2.  Does the root or the stem begin growing first? (The root is first, normally, although sometimes they seem to grow at the same time.)
    3. If the seed is planted upside down, will the plant grow upside down? (No, the plant can sense gravity. The roots will grow down, eventually, and the stem will start up. You may be able to see some initial growth in the opposite direction.)
    4. When do the root hairs appear? (Variable)
    5. What happens to the food supply? (The part that stores the food will shrink as the food is used up and the root takes over feeding the plant.)
    6. Does the part that stores the food stay below ground? (On corn and peas, yes. On beans, supposedly not.)
    7. Can you see the leaves when the stem first appears? (Not really. The corn leaf is encased in a sheath to protect it on its trip through the soil. This sheath is actually the seed leaf. The bean leaf should be hidden between the two seed leaves until it gets above ground. Pea leaves you can see.)
    8. Are the seed leaves shaped like the other plant leaves? (Not usually. They are not as well developed and specialized as regular leaves.)
    9. Do the shoots come straight up or are they hooked to protect the growing tip? (Straight up on corn, hooked on beans and peas.)
    10. Are the leaves green when they first appear? (Usually yellow until they are exposed to light.)
    11. What happens to the seed coat? (It's discarded.)
  1. Remember this observational lesson should be done over a period of weeks. At the beginning the children should observe their beans every other day. Once the seed coat has been broken, the miracle of growth should be watched everyday.

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