Chapter 12 Lesson 3, "Identifying Magnetism"

Materials:

• Worksheet, 11-03 "Identifying Magnetism"

Objective:

• Students will explain what causes magnetism.
• Students will describe how magnetism is destroyed.
• Students will describe how to make a magnet.
• Students will list materials that are attracted by magnets.

Anticipatory Set:* Show this picture of a flower and mention that some things are not attracted to a magnet. No matter how big a magnet is it will not pick up this bunny. Magnets are only attracted to certain kinds of materials. Iron like the heads of these golf clubs is attracted to a magnet, the nickel in these pots and pans will be attracted to a magnet, the cobalt in this rock will be attracted to a magnet, and this steel beam will be attracted to a magnet. Since all these are metal you may think that all metal is attracted to a magnet. That is not true. This nickel is not attracted to a magnet even though nickel the metal is. Ironically a nickel has very little nickel in it. Why is something attracted to a magnet or able to become a magnet?

Teacher Input:* Magnetism starts with the atom within a substance. In the center of this picture you see the particles of a magnet are lined up so that they act as many little magnets within the magnet. This can be expanded to the larger magnet or the world in general. Here is an artist's rendition of what the particles in a substance may look like. There are three different substances here. One that is currently magnetized, one that is attracted to a magnet and one that will never become or be attracted to a magnet, can you tell which is which. Here is an example of what happens to a substance that is attracted to a magnet when a magnet is brought into contact with it. All the particles begin to line up with the particles of the magnet. When the magnet is removed the particles move back to their original position. In this model of a substance would you say this is a magnet, something that could be attracted to a magnet, or something that will not be attracted. How about this other one.

When you look at this picture of paper clips being picked up by a magnet you see that instantly the magnet causes one paperclip to become magnetized and that paperclip can magnetize another. This is because while in contact with the magnet the atoms within the paper clip all line up. When the magnet is taken away the move back to the way they were. It is possible to take something like a paperclip and turn it into a magnet by lining up the particles within the magnet. You need to way to line up the atoms or particles within the substance permanently. Here you see a man pulling a screwdriver across a magnet. With each stroke more and more atoms become lined up. Eventually the the screw driver will pick up its own screws. This can be done with any item that has particles that are attracted to a magnet. Once the particles are lined up you could cut the magnet in half. It doesn't matter how many times you cut it. Each time you will end up with more smaller magnets.

So if we can make a magnet can we destroy one, after all a magnet is often called a permanent magnet? In the case of the screw driver we can just rub it in the opposite direction and this will scramble the particles and demagnetize it. There are a couple other ways to scramble the particles. If we heat a magnet the particles will begin moving and will scramble the particles. You can also hit it with a hammer which would cause the particles to scramble.

Guided Practice:* Students will work in pairs or groups to answer the questions on page 359.

Independent Practice:* Students will read Lesson 3, "Identifying Magnetism" then complete the worksheet, 12-03 "Identifying Magnetism".

Check for Understanding:* Students will take the quiz 12-03 "Identifying Magnetism"

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-1 Students will understand models describing the nature of molecules, atoms, and sub-atomic particles and the relation of the models to the structure and behavior of matter (Structure of Matter);
• SCI A-2 Students will understand the physical, chemical, and nuclear changes and interactions that result in observable changes in the properties of matter (Changes and Interactions of Matter);
• SCI A-5 Students will understand the strength and effects of forces of nature, including gravity and electromagnetic radiation (Forces of Nature);
• SCI A-8 Students will understand the scientific principles and models that
  describe the nature of physical, chemical, and nuclear reactions;
  state that whenever energy is reduced in one place, it is increased somewhere else by the same amount; and
  state that whenever there is a transformation of energy, some energy is spent in ways that make it unavailable for use (Energy Transformations);
• SCI A-9 Students will understand the transfers and transformations of matter and energy that link living things and their physical
• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and: