GOING MY WAY?
How important are magnetic fields to our everyday life? Very
important! Without magnetic fields, there would be no electricity generated,
sailors or pilots would not be able to orient themselves and there would
be no batteries to power our automobiles.
In this lesson, students will investigate how a magnet works and how we
use the Earth's magnetic field to orient ourselves. This lesson is part
of an overall unit on magnetism and is a follow-up to an introduction to
magnetism. In their introduction, students will have "discovered"
what materials are magnetic and what materials are attracted to magnets
by investigating magnets and their properties.
Here's a way to grab your students' attention and focus it on magnetism:
Gather a zip-lock sandwich bag, a breakfast cereal that is advertised as
being "Fortified With Iron," and a small magnet that is painted
white. Place the magnet in a sandwich bag and fill the bag 1/3 of the way
full with the cereal. Seal the bag and shake it vigorously for about one
minute (you can try pulverizing the cereal first if you want to). When you
have finished, inspect the magnet for iron filings attached to it. When
they say a cereal is fortified with iron, they aren't kidding!
Electromagnetism, #1: Earth's Magnetic Field
Students will be able to:
- describe some present day uses of magnetic fields
- draw the shape of magnetic fields around magnets and the Earth
- explain the difference between the geographic and magnetic poles
- describe how we use the Earth's magnetic field to orient ourselves
- demonstrate the proper use of a compass (based on an earlier lesson)
- define magnetism, domain, north and south poles, magnetic declination
- construct their own simple compasses
- graph the results of the magnet and paper clip activity
For each group of four students:
For the teacher's use in the lesson:
- 1 clear plastic container (cups, bowls, or petri dishes will do)
- 1 paper plate
- 1 cork slice (a small piece of sponge will do as well)
- 1 sewing needle
- drop of dishwashing liquid
- 1 bar magnet
- 1 circle, or donut, magnet
- 1 "U" shaped magnet
- 2 gallon-sized zip-lock food-storage bags
- 1 compass (IMPORTANT: KEEP COMPASSES AWAY FROM MAGNETS AT ALL TIMES!
THE POLARITY OF THE NEEDLE COULD BE PERMANENTLY DISTORTED.)
- iron filings
- water (enough to fill the above clear container 3/4 full)
- 2 rulers
- 2 pieces of string about one foot long
- 1 pair of scissors
- 1 roll of masking tape
- 1 box of about 100 small paper clips
- 1 bowl (or container slightly larger than the bar magnet)
- 1 felt tip pen
- 1 pencil
- 1 sheet of large squared graph paper
- 1 box clear plastic wrap
- 1 overhead projector
- 1 set of overhead transparency markers
- 1 TV monitor
- 1 sheet of acetate taped to the TV screen to be drawn on
- 1 large white poster board
- 1 roll of masking tape (to tape poster board to wall)
- 1 sandwich-sized zip-lock food storage bag
- 1 box of breakfast cereal advertised as being "Fortified With
- 1 small magnet (any type) painted white
Present the following question to the students: " Does
a magnet have equal attraction, or grabbing power, everywhere on its surface;
or, does one part of a magnet have a stronger attraction than another?"
After polling the class for their hypotheses, post the results on the blackboard.
Next, solicit suggestions for developing an experiment to see how we can
find out the answer to our question.
Divide the class into groups of four students each and give each group a
gallon-sized zip-lock food storage bag containing two lengths of string
about one-foot long, masking tape, bar magnet, box of about 100 small paper
clips, and a container slightly larger than the magnet.
Have the groups complete the following procedures: Tie one string to each
end of the bar magnet. Tape the other end of each string to the edge of
a desk or table (making the magnet level), leaving sufficient clearance
from the floor to maneuver the container under it. Spread the paper clips
in the container and raise the container under the magnet slowly until the
magnet rests on the clips. Slowly remove the container from under the magnet.
Observe where the clips cling to the magnet. Record observations, and include
a short written description as well as a drawing.
When each group has completed their activity , have a representative from
each group present their results to the class and discuss them. Discussion
should include the observation that more clips attached themselves to the
ends of the magnet than anywhere else.
Select one of the student drawings to temporarily post on the lefthand side
of a large piece of white poster board taped to the blackboard.
At this point, ask the class if they can think of a way of making the invisible
lines of force plain to see. Ask questions like "How many of you have
ever seen a magnetic toy that you can draw with?" This should help
cue them to thinking about little pieces of something that the magnet can
move. Explain that those little bits of something are metal filings. We
get filings by running a piece of metal over a file. The little bits that
get scraped off are filings. These filings are made from iron, one of three
special metals that can be magnets, or can be attracted to magnets. (The
other two metals are nickel and cobalt.) Hold up your container of iron
filings and explain we can make some of the invisible lines of force easy
to see by sprinkling some filings on a piece of paper laid flat over a magnet.
Instruct each group to lay their bar magnet on a level surface, such as
a desk or table top, and cover the magnet with a piece of paper that is
stiff enough not to flop over the magnet, yet not too thick that the magnetic
field is shielded by it. Visit each group and dispense some iron filings
to be spread on the paper. Instruct the students to observe any patterns
they see, sketch them and write a short description of what they see. Meanwhile,
turn on the overhead and project the image on the piece of white poster
board next to the student drawing of the paper clip exercise. Place a bar
magnet on the surface of the projector and cover it with a blank sheet of
overhead transparency. Sprinkle some filings on it and distribute them evenly.
This should duplicate the results the students are observing and will provide
a comparison to the student drawing of the paper clips. Most of the filings
should be clustered about the poles of the magnet, making it visible why
the paper clips were also attracted to these areas. Discuss the magnetic
lines of force and magnetic fields with your students.
As a follow-up activity, have the students explore the strength of the poles
of differently shaped magnets to determine if the shape of a magnet affects
its areas of strength. To accomplish this, do the following:
Have each group tape one bar, donut and "U" shaped magnet to a
desk or table top so that each magnet hangs over the edge.
Space them far enough apart so one doesn't affect another.
Bend open the end of a paper clip so that it forms a hook and attach one
to each magnet at one pole. (The poles for the bar and "U" shaped
magnets are at their ends. The poles for the donut magnet are the flat circular
surfaces.) Do not hook it over the magnet.
To each magnet, attach one paper clip at a time to the hook and count how
many clips each hook can hold. Try several runs through this exercise and
graph the average.
Keep records of the results and graph them. (Review the four parts of a
graph: the title, a label for each axis, and the data. A bar graph is best
suited for this exercise.)
To give students a specific responsibility while viewing, ask
students to be on the lookout for the following information throughout the
course of this video: modern day uses of magnets and magnetic fields the
history of magnets the construction and use of a compass the shape of magnetic
fields around a bar magnet and the Earth the definitions of magnetic poles
and magnetic declination the difference between geographic and magnetic
You might want to post these items on an overhead projector or poster. The
following page is a template from which you can make an overhead transparency.
You can also make copies for the students to have at their desks to jot
down some notes as they go along.
Going My Way? Focus For Viewing
Be on the lookout for the following information which will be discussed
after viewing the video:
Modern day uses of magnets and magnetic fields.
The history of magnets.
The construction and use of a compass.
The shape of magnetic fields around a bar magnet and the Earth.
The definitions of magnetic poles and magnetic declination.
The difference between geographic and magnetic poles.
Show opening sequence from "Aliens would shut down a city
if they could neutralize all magnetic fields."
PAUSE video when narrator says, "For the moment, however, this
is only science fiction."
Ask: -"What does neutralize mean?"(to destroy or counteract a
force - in this case magnetic fields)
Ask: "What would neutralizing magnetic fields have to do with cars
and office buildings?" Have students hypothesize (part of their scientific
method vocabulary) and give possible answers. (Magnetic fields are used
to generate electricity and battery power.)
Re-alert students to look out for what civilization discovered magnetism.
Why is a lodestone (magnet) called a magnet? How were early compasses made?
PAUSE: "These mysterious pieces of stone advanced sea exploration
as never before."
Ask: "How did these stones advance sea exploration?" (They helped
sailors find their way over great distances. By knowing which way was north,
all other directions can be found.)
Ask above questions that students were alerted to and discuss student answers.
PAUSE: at spherical lodestone graphic where the narrator says, "So
a compass placed anywhere on the lodestone sphere will align itself with
the magnetic field."
Review the three diagrams posted on the blackboard.
Alert students to listen for the difference between the geographic and magnetic
FAST FORWARD to the graphic of Earth in space after the heating of
the magnet is shown. CONTINUE video where the narrator says, "But
these magnetic poles do not coincide with the geographic poles of the Earth."
PAUSE: at graphic of the Earth in space with both sets of poles displayed.
Ask: "What are the geographic poles?" (The points on the Earth
where the imaginary axis runs through. Review that the Earth spins on its
axis once every 24 hours giving us our night and day.) Ask: "What are
the magnetic poles?" (Review earlier information that the magnetic
poles mark where the lines of force are closer together at opposite ends
of a magnet or the Earth.)
Ask: "Will a compass point to the geographic north pole?" (No.
From most places on the Earth, it will not.)
STOP video after the graphic of the magnetic north pole marker zig-zagging
around the globe.
Review the items the students were alerted to prior to watching the video.
Use the worksheet provided earlier as a guide.
For the post-viewing activity, each group of students will construct
their own simple compasses. Use the following page, labeled "Going
My Way? - Activity #1," as a handout for the students. You can also
use it as an overhead to help walk the class through the entire set of instructions
before actually trying them.
Once the compasses are constructed and have been verified by the "real"
compasses, have the students construct a map of the classroom and/or schoolyard.
Using their hand-made compasses, the students need to identify the directions
in which several objects lie about the classroom/school yard, use symbols
to identify them and orient the maps accordingly. Have the students follow
the directions on the sheet labeled "Going My Way? - Activity #2"
to help them in this exercise.
Invite sportsmen and women (hunters and hikers especially),
as well as airplane pilots or sailors (professional and amateur) to the
classroom to discuss and/or demonstrate the importance of a compass to their
sport or livelihood.
Visit your local airport or marina to discuss the importance of a compass
Contact your local Boy Scouts of America supplier and request a set of orienteering
games and play them in your schoolyard (space permitting).
Make your own compass rose on your school grounds. At noontime, the Sun
is due South from you. This means any shadows it casts are falling in the
due North direction. Once you have North marked, South is directly behind
you, East is to your right and West is to your left. Try placing the intercardinal
directions of Northeast, Northwest, Southeast and Southwest too!
Mathematics: design a compass course to be completed
on school grounds specifying distance and direction.
Art: draw a map of the school grounds and include a key explaining
the scale, symbols and directions.
Physical Education: perform the above compass course.
Social Studies: tie into unit on map and globe skills.
Science: tie into a unit on the Earth's atmosphere, especially regarding
the northern and southern lights and their relationship to the Earth's magnetic
poles (just as the magnetic lines of force are closest together at a magnet's
poles, so too are they at the Earth's poles. When electrical particles from
the Sun reach the Earth, they gather at the poles producing glowing lights
in the sky).
Language Arts: Read The Hatchet by Gary Paulson. It's a story about
a boy who crashes in an airplane and uses all his resources to help him
Master Teacher: Daniel Reidy
Lesson Plan Database
Thirteen Ed Online