Life Cycle - Human Biology (1A)
Post Lab 

  • Exploring the central nervous system.
  • Discovering how the nervous system sends messages to the brain.
  • brain
  • nerve
  • spinal cord
  • yarn 
  • worksheet 
  • glue
  • brain mold (optional)

Students make a yarn diagram of the nervous system.


The central nervous system is controlled by the brain.  The central nervous system includes the spinal cord, the brain, and an entire network of nerve fibers that run throughout the body.  Unlike the circulatory system which forms a closed loop, the nervous system has "endings."  This exercise will help students to visualize the pathways of these nerves.  The brain is an incredibly complex organ that is the center of thought and all involuntary motions.  The brain maintains the body in working order by overseeing the functions of all organs and body systems.  The spinal cord is a soft, fluted column of nerve tissue continuous with the lower part of the brain and is enclosed by the bony vertebral column.  This nerve tissue lies within the vertebral column; the bone is there to protect the tissue.  There are 31 pairs of spinal nerves which emanate from the spinal cord.  These nerves provide pathways for impulses to flow throughout the body and to the brain.  

  1. In this exercise the students will use the worksheet to see how the central nervous system is connected with the brain.  Students should  cut and paste yarn over the system.  The darker lines illustrate the  31 pairs of spinal nerves that begin at the spinal cord.
  2. Instruct the students to count the number of spinal nerves first, and then direct them to trace the major ones with the yarn. Make sure that the nerve paths end and are not looped. 
  3. You may want to prepare a jello “brain mold” for students to look at.  Since the brain is considered the “nerve” center of the body, this activity emphasizes the brain’s importance.

    Ingredients for brain: 

    two 6 ounce boxes of gelatin mix (any flavor, but peach or watermelon give a more realistic color)
    1 ¾ cups boiling water
    1 cup cold water
    9 ounces fat free evaporated milk - don’t use any kind but fat free or it will curdle
    food coloring: about 15 drops each of red, green, and blue with make a gray brain, but any colors will work


    1. Before each use, wash the brain mold with warm soapy water.
    2. Spray or smear the inside of the brain mold with a small amount of vegetable oil.
    3. Put the gelatin mix in a large bowl and add the boiling water.  Stir about 2 minutes until the mixture is dissolved.
    4. Stir in 1 cup of cold water.
    5. Add the evaporated milk and food coloring and stir well.  Adjust the color to your liking.
    6. Pour the mixture into the brain mold, stopping about ¼ inch from the top.
    7. Place the brain mold in a shallow bowl so it will sit level, and refrigerate overnight or until firm.
    8. To remove your brain, shake the mold until the gelatin loosens.  Place a flat plate upside down over the open side of the mold, then flip the mold and plate together.  Lift the mold off, leaving the brain on the plate. 

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