Activity 13

Lesson Topic: Magnetism, Latitude and Longitude, Compass DirectionObjectives: This is a two-step hands-on activity that has students examining the concept of magnetism and building a compass using these newly learned concepts of magnetism. Students will learn how bar magnets work, how to magnetize a metal object, how to build a compass using magnetism, and how to operate a compass.NCTM Content Standard Objectives:

Physical Sciences Properties of objects and materials

Light, heat, electricity, and magnetism

Motions and forces Science and Technology

Abilities of technological design

Understanding about science and technology

Ohio Science Academic Content Standards: Students demonstrate an understanding of the composition of physical systems and the concepts and principles that describe and predict physical interactions and events in the natural world. This includes demonstrating an understanding of the structure and properties of materials and objects. Students will also recognize that science and technology are interconnected and that using technology involves assessment of the benefits, risks, and costs. Students should build scientific and technological knowledge, as well as the skill required to design and construct devices.Materials:

2 bar magnets

Sewing needle

One straw Plastic bowl or dish Water

Small sticker

Sharpie marker

Compass (if desired) Understanding Magnetism worksheet

Building a Compass worksheet

Magnetism and the Poles Concept Sheet :

What is magnetism? It is an invisible force that attracts certain metals, like iron. This force is something that pushes or pulls an object. Any material that creates this force is called a magnet and are said to be magnetic. Magnets have two polesnorth and south. They will pull toward, or attract each other, or repel each other, according to which ends are pointed towards each other.

Some natural rocks can be magnetic due to having a type of iron material: magnetite. Scientists believe magnetite has been magnetized by the earths magnetic field when the material hardens and cools from its molten state.

The area around a magnet in which objects are affected by its magnetic force is called its magnetic field. The magnetic force of a magnet is stronger close to the poles of the magnet. The Earth is actually like a huge bar magnet. It has a north pole and a south pole just like bar magnets. Any magnets located close to the Earth will point in approximately the same directiontoward the North Pole. A compass is a small magnet that is free to move on its axis. Due to the Earths magnetic field, the compass magnet will always align itself in a north-south direction. Instructional Strategy:

Part One: Understanding Magnetism1) Instruct students to bring the south pole of one bar magnet near the south pole of another bar magnet. Then bring the two north pole ends together. Have the students record results on their worksheets.

2) Now instruct students to bring the south pole of one bar magnet to the north pole of another bar magnet and vice versa. Have the students record results on their worksheets.

Part Two: Building a Compass

1) Fill a small bowl or dish about halfway with water. This will be the body of your compass.

2) Use the metric end of a ruler to measure a straw. Using a Sharpie marker, make a mark at about 50 mm.

3) Using scissors, cut the straw at the line, and keep the 50mm measured portion.

4) Use a sewing needle that is about the same size as the piece of cut straw. Magnetize the needle by rubbing the needle anywhere on a bar magnet for about 5-10 seconds, or 100 times. The needle is now your magnet!

5) Place the magnetized needle inside the piece of straw.

6) Place the straw (with the needle inside) onto the surface of the water. Make sure you did not place the original bar magnet anywhere near the needle and straw or the bowl of water. Also, make sure the needle and straw do not break the surface of the water. If they sink, dry them before replacing them back on the surface of the water. The straw with the needle is now your compass needle.

7) Determine the north and south poles of your compass needle using a bar magnet. To do this, place the south pole of the bar magnet near your compass needle. The end that is attracted to the bar magnet is the north pole of your compass needle (because opposites attract), and the other end is your south pole.8) Place a small sticker or marker mark on the north pole end to distinguish it from the south pole end of your compass needle.

9) Observe the compass needle. Compare it to the direction of a store-bought compass.

Understanding Magnetism WorksheetName:__________________________

Date:___________________Directions: Use two bar magnets that are the same size to answer the questions below:

1) Try to touch the two south poles together. What happened to the magnets? Do they push each other away from each other or do they pull each other together?

2) Try to tough the two north poles together. What happened to the magnets? Do they push each other away from each other or do they pull each other together?

3) What happens when you touch the north pole of one magnet to the south pole of another magnet? Do they push each other apart or pull each other together?

4) Draw a picture of a bar magnet below. Label the north and south pole of your magnet.

Building a Compass Worksheet

Name:__________________________

Date:___________________

Directions: After you have completed building your own compass answer the questions below:

1) Why do the same poles of two magnets repel each other?

2) Why do opposite poles of two magnets attract each other?

3) What does a compass help us to determine?

4) Why do you think the needle of a compass point towards the north?