Magnets---Polarity

Prerequisite Knowledge

Magnets can attract some objects, including other magnets.

Process Skills

Observation, classification, communication, prediction, inference, experimentation, and defining operationally.

Materials

Magnets (disk and bar), children, mazes, 1/8-inch dowel rod (6-inch-long sections), playdough, paper clips.

Performance Objective

Students will identify and describe the poles of a magnet. They will demonstrate how the poles interact with one another.

Exploration Phase

1. Have all the students stand in a circle facing the center. Explain the rule: if they are facing the same direction, they cannot touch each other. If they are facing in the opposite direction from their neighbors, they need to make a connection and hold hands.
2. Have every other child turn around and face away from the center. Ask if the students see any connections that can be made. Have everyone face the center again.
3. Repeat the exercise about three times. Each time, use a different pattern of selecting children to face away from the center: 2 in, 1 out; 3 in, 2 out; etc. After each selection, ask the students to look for connections that can be made.

4. Have children work in pairs with the child who sits next to them in the classroom. Give each child a magnet and have the pairs “play” with the magnets together. Refer back to the earlier activity: “Think about how your magnet acts with your partner’s magnet.”

   • “Do you notice anything interesting about how the magnets work together?”
   • “Do the magnets like each other by going together, or do they act like they don’t want to be together?” “Anyone else notice anything?”
   • “Do all of your magnets do that, or do just some of the magnets act that way?”

Concept Introduction Phase

1. “Why do you think the magnets are attracted to each other sometimes, and at other times they don’t want to go near each other?”

   Listen to ideas from several students.

2. “We have some words that describe how the magnets are acting. You heard me say that the magnets are attracted to each other. What does it mean for magnets to be attracted to something?”

   “The opposite of attraction is called repulsion, and that means that it pushes away.”

   Show two magnets being attracted to one another. “I can make the same two magnets show repulsion by turning one of them around like this.”

   “Every magnet has two poles, a north pole and a south pole. The poles are on the ends of the magnets. Earlier, when I had you hold hands if you were facing in opposite directions, you were acting like magnets, and your hands were the poles. When you were the same, you couldn’t touch, and that is what happens with magnets. The poles have to be different for the poles of two magnets to touch. How many have ever heard the phrase ‘opposites attract’? That’s a very easy way to remember about magnets. The north pole always wants to be next to the south pole because they are opposites.”

Concept Application Phase

Maze Activity: If Enough Small Bar Magnets Are Available

I do have a few long bar magnets. I would prefer to have the students design their own mazes, but can’t always do that because of time constraints.

1. Pass out mazes. “I want each pair of students to think of a way to get one of your magnets to go through the maze by touching only the second magnet. Once the two of you decide on how to get through the maze, I want you to see if your method works. Your magnets cannot touch one another. As soon as you have figured out how to get through the maze, raise your hand, and either Ms. Lewis or I will come over and you can show us how you did it.”

   Review the instructions by asking: “What do I want you to figure out?” “What are you going to do after you’ve figured out a way to get through the maze?”

2. Once the students raise their hands and show how they get through the maze, ask questions about how they figured out what to do and why it worked. In their explanations, listen to see if they describe how the poles of a magnet work with and against one another.

Floating Magnet Activity: If Enough Bar Magnets Are Unavailable

If I can’t get enough bar magnets, I’ll use the disk magnets I already own.

1. “Each pair of students is being given a dowel rod and a chunk of playdough. Make a ball out of the playdough and set it on one of the desks, and then put the dowel rod in it so that it stands up like this.”
2. “I want you to figure out a way to put your magnets on the rod so that one of the magnets will float above the other magnet. Once you’ve figured out how to do it, raise your hands, and either Ms. Lewis or I will come over and you can explain what you did.”
3. Once the students raise their hands and show their solution, ask questions about how they figured out what to do and why it worked. In their explanations, listen to see if they describe how the poles of a magnet work with and against one another.

Further Exploration

Compare the strength of the two poles of a magnet.

“Do you think one part of the magnet is stronger than the other parts of the magnet?” “Which part do you think will be stronger?”

Spread paper clips on the table. Place the magnet on top of the paper clips, and then lift. “What parts of the magnet are the paper clips attracted to?”

Count how many paper clips are stuck to each pole of the magnet. “Are there different amounts?” “What part of the magnet had fewer paper clips stuck to it?” “Does this tell you anything about the magnet?”