Academy Curricular Exchange
Columbia Education Center 
Science


Theresa Figarelli, Jefferson Elementary, Everett, WA

                        USING MICROSCOPES

Appropriate for grades 3-6.

OVERVIEW:  This activity is used during a unit about cells.  I use
it to give the students the opportunity to see cells and to
discover the difference between plant and animal cells.

PURPOSE:  To further the students understanding of cells and to
give them the experience of using a microscope.

OBJECTIVES:  The students will be able to:

 1.  Describe the differences between plant and animal cells.

 2.  Operate a microscope.

 3.  Examine cheek cells, onion cells, and potato cells.

ACTIVITIES:  

 1.  How to Use a Microscope:  The teacher will need to prepare a
     worksheet for the students showing a diagram of a microscope
     labeling all of its parts.  The teacher will then provide the
     students with microscopes and guide them through an
     introduction to the following parts from top to bottom:

          Eyepiece 10x
          Body tube
          Revolving nose piece
          Objective lens 4x (low); 10x (medium); 40x (high)
          Stage
          Stage clips
          Carrying arm
          Mirror or light source (lamp)
          Base

 2.  Setting Up a Wet Mount Slide:  The teacher explains that a
     wet mount slide gets its name because it is wet with either
     stain or water.  Stains are used to color parts of cells so
     they may be seen easily.  In order to view something with a
     microscope a person must be able to see through it.  The
     object must let light through it - this means translucent.

     The teacher then demonstrates how to make a wet mount slide.
     Then the student will advance to prepare their own slides for
     observation.  The teacher may draw the following diagram on
     the board and describe what she will do with the materials.

     A wet mount slide includes the following:  a slide, a cover
     slip, a specimen, a drop of stain or water.  When preparing a
     slide, hold the cover slip at an angle (as shown in the
     diagram above) and let it drop onto the slide slowly trapping
     the specimen between the two pieces of glass.  A piece of
     onion skin is easy to use in this first activity.



 3.  Observing and Comparing Cells:  Depending on the age of the
     students the teacher may choose to read the following
     directions to his/her students or share them on a worksheet:

     Onion Skin

      a.  First take a piece of onion skin off the onion.
      b.  Put it flat on a slide.
      c.  Bring the slide to the leader for a drop of iodine
          stain.
      d.  Carefully put on a cover slip remembering to angle it.
      e.  Examine the cell under low then medium power.
      f.  Ask the teacher to put it on high power.
      g.  Draw a few cells showing what you observed in the space
          provided.
      h.  Describe in a few sentences what you saw while looking
          at the cell through the microscope.

     Cheek Cells

      a.  Using a toothpick scrape the inside of your mouth.
      b.  Place it carefully on the center of the slide.
      c.  Bring it to the leader for a drop of blue stain.
      d.  Repeat steps d-h from onion skin directions.

     Potato Cells

      a.  Using a knife carefully cut a very thin slice of potato.
      b.  Have the leader add a drop of iodine stain.
      c.  Repeat steps d-e from onion skin directions.
      d.  Draw a few cells in the space provided.
      e.  Describe what you saw.

Now the teacher facilitates a discussion comparing and contrasting
what the students observed.  The following vocabulary should be
discussed and or defined:

     Cell Walls       Plants have thick cell walls to strengthen
                      the plant stem.

     Cell Membranes   Animals have thin membranes because they
                      have other forms of skeletons.

     Chloroplasts     Green colored structures that produce food.

     Nucleus          Both plants and animals have these; they
                      control heredity and cell division.

     Cytoplasm        A clear liquid where most of the cells life
                      functions occur.

After the discussion the students should have the opportunity to
observe the slides again so they may observe the items discussed.

RESOURCES/MATERIALS NEEDED:  Microscopes, slides, coverslips,
potato, onion toothpicks, knife, iodine stain, blue stain, and
worksheets.


TYING IT ALL TOGETHER:  This activity has been used in cooperative
learning groups consisting of students of mixed ages grades 1-5. 
Also it has been used several times in fifth grade classrooms. 
The students enjoyed the experience and were able to learn the use
of a microscope and depending on the age, gain a better
understanding of cells.  This is the best beginning microscope
lesson I have found.  It is especially useful for the fifth grade
unit on cells.  The students learn more about cells through actual
observations than looking at textbook pictures.
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