Introduction to magnets

General

Students are introduced to magnets and learn about the basic workings of magnets and magnetic forces.

Standards

NGSS: MS-PS2-3

Learning objective

Students will be able to describe how magnets exert force from a distance.

Introduction

Start the lesson by having students work in pairs to complete a KWL chart to brainstorm about what they already know and want to learn about magnets. After completing these KWL charts, discuss a few of the things that students know or want to learn as a class.

Instruction

Introduce students to magnets. Discuss the magnets that they likely already are familiar with—the kind that stick photos and drawings to the fridge. Explain that magnets can do more than stick things to the fridge, they sometimes seem like magic, but all can be explained with science. Define that magnets are objects or materials that attract iron and generate an invisible magnetic field. Discuss the history of magnets and where some of the first magnets came from. Explain that magnets and their invisible magnetic field have two poles: one North pole and one South pole. (You can challenge students to come up with what else has a North Pole/South Pole: the Earth!) To discover where the north and south magnetic poles are on Earth, hand out rectangular bar magnets and string to the students in the class. Have students tie the strings around the middle of the magnets (or pre-tie to speed up the process). Ask students to hold the magnets just like in the image on the interactive whiteboard. What happens to the magnet? Explain that the magnet will align itself with the magnetic field of the earth and that the north pole of the magnet will line up with the (magnetic)north pole of the earth, and the south with the south pole. This is a simple compass like the ones people have used for hundreds of years! Next students are asked to investigate how magnets exert forces on each other without touching. This is an exploration of the magnetic field of magnets. Either untie the string from the bar magnets or give each student (or group/pair) a pair of magnets. Students are asked to match their magnets with the magnets in the image on the interactive whiteboard. Be sure to have students describe what is happening as they try to put S to S, S to N, and N to N. In discussion of the movement of the magnets, teach students the words repulsive and attractive as the types of magnetic force that is being exerted between the magnets. Like poles (S/S, N/N) repel each other and opposite poles (N/S) attract. As the magnets get closer together, the magnetic force gets stronger. Discuss how magnetic fields are invisible but can be felt or act on objects around them. Have students draw a magnetic field around the given bar magnet.

Quiz

Students are asked to define key concepts given in the lesson and then asked to determine if magnets placed close together will exert an attractive or repulsive force. Be aware that many have multiple correct answers.

Closing

Discuss what you have learned about magnets and how you now have proved that magnets exert force on each other and objects around them. Close by completing the KWL charts with some of the key takeaways from the lesson.