TITLE:  Photosynthesis and Transpiration

AUTHOR:  Nelida Boreale

GRADE LEVEL:   6-8

OVERVIEW:  Many students are not interested in science at
all.  They often think that the concepts taught in science
are irrelevant to their needs.  They think that science is
boring and hard.  Until children experience science in a
fun way, their attitude toward science won't change.

PURPOSE:  The purpose of this lesson is to help students
experience science in a different way.  To change students
negative attitudes toward science into positive.

OBJECTIVES:
  1.  To observe the effect of light on plants.
      Illustrate the exchange of gases between the
      atmosphere and the plant.
  2.  To understand how green plants use the sun's energy to
      produce food through photosynthesis.
  3.  To see that plants are part of many natural cycles.

RESOURCES/MATERIALS:  Two or more six inch pots, fifty or
more pea seeds, vermiculture soil mix (or potting soil)
a sprinkler (a jar with holes in the lid), a dark area (a
large cardboard box) or a cabinet A glass bottle or jar,
paper, pencils, crayons

INTRO:  Plants provide a renewable source of food energy for
many forms of life. Green plants utilize the sun's energy
and the gases in the atmosphere to produce food through
photosynthesis and exchange gases in the atmosphere in the
associated process of transpiration.

ACTIVITIES AND PROCEDURES:
1)   Have the class divide into small groups (if not
     conducting this experiment as a demo.)   Have each
     student make an illustrated log of events for
     germination of the seedings to the end of the
     experiment.
2)   Germinate pea seeds by placing them onto damp paper
     towels in a tray or shallow dish and covering them with
     warm tap water.  Keep covering them with warm tap
     water.  Keep covered with warm water and in a
     indirectly lit place.  A "hook" should appear in two to
     three days.  After the "hook" appears, the seeds are
     ready to be planted in the pots.
3)   Prepare two pots by placing paper towels as a lining
     for each pot.  Fill with the vermiculite soil mixture
     up to 2 1/2 inches from the top.
4)   Place the seeds carefully on top of mixture.  Cover
     with 1/4 to 1/2 inches of soil mix.
5)   Sprinkle water over the top of the soil until the soil
     is well saturated.
6)   Place one of the pots in a well lit place.
7)   Place the other pot in the designated dark area and
     leave it completely in the dark for one week to ten
     days.
8)   At the end of one week or ten days, remove the pot from
     the designated dark area and compare it with the pot of
     seedlings that were grown in the light.
9)   Have the class discuss the differences and make a
     drawing to illustrate the differences between the two
     sets of seedlings.
10)  Leave the pot that was in the dark in the light for a
     few days, and compare the results.
11)  Remove one seedling from each pot and compare the root
     structure of the dark grown seedlings and the light
     grown seedlings.
12)  Place a glass bottle over one of the seedlings, and
     place it in the sunlight.
13)  Notice the condensation that occurs on the inside of
     the bottle. The condensation is water vapor being given
     off by the plant when it exchanges oxygen for carbon
     dioxide. (transpiration)

EXTENSIONS:

1)   Take the class out to a grassy area on the school
     grounds. Dig up a shovelful of grass covered soil.
     Have the class examine the depth of the roots and their
     structure.
     How do they differ from the pea seedling roots?  How
     does grass differ physiologically from the pea
     seedlings? (stems leaves, etc.)  Do they have the same
     photosysnthetic process?
2)   Take the class to a treed or forested area.  Compare
     the effect of light on identical seedlings growing in
     the shade of a tree and seedlings growing in sunlight.