Discuss the role of models in science-specifically, the models of the brain that students use in this unit.
Draw students' attention to the Key Ideas using means such as posters and overhead transparencies.
Introduce the section with the Journal Writing prompt to invite students to think about their brains.
Engage students in a discussion about the brain, using comparisons such as “mission control.”
Introduce the term homeostasis, or “balancing the steady internal environment of the body with the changing external environment.” Use the seesaw analogy.
Discuss the importance of the structure of the brain and its connection to the sensory organs.
The Mini Activity: Egghead emphasizes the role of the skull in protecting the brain.
Discuss the role of bike helmets and hard hats as they relate to protecting the brain from injury.
Discuss the function of the blood-brain barrier when students do Activity 1-1: The Blood-Brain Barrier.
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Suppose for a minute that brain transplants were possible, as in a science fiction movie. If you had a brain transplant, would you be you, or would you be the person who donated the brain? Why?
The study of the nervous system is called neurobiology. What do you call someone who studies neurobiology? What subjects do you think a person would have to study to become a scientist who studies neurobiology?
Billions and Billions
Students count kernels of corn contained in a cup to calculate one billion.
What Do You think?
Think about what you have learned about the brain so far. Now think about the bike helmet laws in effect in many areas. These laws, which are sometimes controversial, require anyone riding a bicycle to wear a helmet. Do you think a bike helmet law is a good idea? Is such a law fair? Explain your responses.
Egghead This activity can be used as a student project for demonstration to the class. It is important that the jar is completely filled with water and without any space or air. Teachers need to check jars to be sure they do not leak. When students give the air-filled jar a slight shake, the egg in the jar will break. However, even with vigorous shaking, the egg in the water filled jar will not break. Refer to Activity 2-1: Big Brain on a Stick to discuss how using a bike helmet protects the brain.
Ask Students How is the egg in the jar of water protected?
The water cannot move out of the way when the jar is jolted. This is why the egg doesn't hit the side of the jar and break.
What would happen if the glass jar containing the raw egg and water fell onto the ground? (Do NOT test their hypotheses!)
The jar would shatter and the egg would probably break.
Activity Extension Remove eggshell with vinegar before placing it in the jar (This takes about 24 hours.) The membrane around the egg can represent the meninges, the tough outer membrane protecting the brain. The uncooked egg representing the brain is more like the consistency of a real brain. Infection of the meninges is called “meningitis.”
Have students design a protective covering for the egg in a jar of water model so that the jar would not break after being dropped from a height of 6 feet, maximum.
Suggestions: Use contest format, document with photos or videotape. Make connections with use of bike helmets to protect the skull (jar) and brain (egg) from damage. Ask students to suggest methods of protecting the brain portion (the egg) of the model only. Some suggestions could include wrapping it in a soft material to cushion against shock or covering it with a hard material to protect against blows. Solicit student suggestions for examples of materials that could be used for this protection. Have students compare their methods of protection for the brain to the skull and cerebrospinal fluid.