Magnetism #20

(grades 8-12)
Soft-bound, 72 page book, 28 reproducible task cards, full teaching notes.

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Magnets are fascinating. They provoke our curiosity. Touch a magnet to a straight pin to make another magnet. Hang this pin on a thread to make a compass. Use it to map magnetic fields around a small magnet, or a whole planet. Reverse poles on your pin, chop it into pieces, heat the attracting fragments in a candle flame. These experiments reveal much about the nature of magnetic domains. Create a surprising array of wonderful inventions: electromagnets, solenoids, telegraphs, buzzers, motors, generators and relay switches. What fun (and great science)!

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Table of Contents for #20 Magnetism:

Preparation and Support

A TOPS Model for Effective Science Teaching • Getting Ready • Gathering Materials • Sequencing Task Cards • Gaining a Whole Perspective• Long Range Objectives • Review/Test Questions

Activities and Lesson Notes

  1. 1. The Basics
  2. 2. Force Field
  3. 3. Build a Compass
  4. 4. Angle of Declination
  5. 5. Pin Chains
  6. 6. Magnetic Domains
  7. 7. Rearranging Domains
  8. 8. Lines of Force (1)
  9. 9. Lines of Force (2)
  10. 10. Lines of Force (3)
  11. 11. A 3-Dimensional View
  12. 12. Interacting Fields
  13. 13. Terra Bagga (1)
  14. 14. Terra Bagga (2)
  15. 15. Coil It (1)
  16. 16. Coil It (2)
  17. 17. Rocking Galvanometer
  18. 18. Electromagnet
  19. 19. Solenoid
  20. 20. Telegraph It
  21. 21. Buzz It
  22. 22. On-Off Motor

  24. 23. Reverse Poles Motor (1)
  25. 24. Reverse Poles Motor (2)
  26. 25. Relay Switch
  27. 26. Motors and Generators
  28. 27. Inverse Square Law (1)
  29. 28. Inverse Square Law (2)

Supplementary Pages

polar map • centimeter ruler • compass base • protractor • millimeter ruler • graph paper


Complete Master List for #20 Magnetism:

Key: (1st/2nd/3rd) denote needed quantities: (1st) enough for 1 student doing all activities; (2nd) enough for 30 students working in 10 lab groups all self-paced; (3rd) enough for 30 students working in 10 lab groups, all doing the same lesson. Starred* items may be purchased below.

  1. * 2/20/20: rectangular ceramic magnet
  2. * 1/2/2: rolls masking tape
  3. 1/10/10: scissors
  4. * 1/2/2: boxes paper clips
  5. * 1/1/1: spool thread
  6. * 2/20/20: wooden spring-type clothespins
  7. * 3/20/30: baby food jars (or small beakers)
  8. 1/6/10: meter sticks
  9. 5/50/50: blank index cards
  10. * 10/10/10: steel straight pins

  11. * 1/1/1: roll aluminum foil
  12. 1/6/10: marking pens, black or other dark color
  13. * 10/100/100: meters thin insulated wrapping wire, 30-32 gauge
  14. * 1/10/10: meters copper or aluminum wire, 20-24 gauge
  15. * 1/1/1: 8 cm pieces of very thin, bare, copper or aluminum wire, 32 gauge or less
  16. 1/4/10: medium-sized empty cans
  17. 1/4/10: wire cutters
  18. * 1/4/10: candles and matches (or alcohol lamps or Bunsen burners)
  19. * 2/20/20: straight drinking straws
  20. 2/20/20: textbooks of equal thickness

  21. 1/2/5: exterior windows for tracing onto paper (or light tables)
  22. * 1/4/10: rectangular pocket mirrors (optional)
  23. * 1/1/1: roll clear tape
  24. 1/4/10: hole punch
  25. * 0.1/1/1: cup modeling clay
  26. * 1/10/10: size-D dry cells with magnetic outside casings
  27. 1/10/10: large paper grocery bag (or heavy wrapping paper)
  28. * 5/50/50: rubber bands, medium width or wider
  29. * 2/10/20: large nails, 3 1/2 inches long
  30. * 50/500/500: washers to fit onto large nails, with holes smaller than the nail head

  31. * 1/10/10: feet wood dowel, 3/16 inches in diameter
  32. 2/20/20: thumbtacks
  33. * 1/3/10: gram balances, those improvised in #05 Weighing are suitable

Convenient Shopping:

Aluminum Foil

regular strength, 20 square feet x 12 inches rolls

Buy aluminum foil here as a convenience item, or for less in many grocery stores.

Baby Food Jars - assorted

without lids

Each set includes 4 small, 4 medium and 4 large glass jars.


size-D, alkaline

These are basic workhorse brands, available everywhere.

Candles - emergency

cylindrical, 5 inches by about 3/4 inches diameter

Also called utility candles. A handy heating source. Correctly sized for #09 Floating and Sinking. Drip catchers not included.

Clay - modeling

oil-based, non-drying

Sold by the 100 gram stick, about 1/4 cup, in assorted colors (our choice). One stick serves a whole classroom for TOPS applications.


wooden, spring-action

These are handy lab items to keep in stock. We use them as bulb holders, tongs, clips, and more.

Dowel - thin

wood, 3/16 inch diameter by 6 inch length

This diameter fits the hole in our ceramic refrigerator magnets. Needed for #20 Magnetism.

Gram Pocket Scale

digital, pocket size

Digitally weighs up to 500 grams, plus tare container. Sensitive to 0.1 gram in multiple weight units. Durable, but not childproof. Comes with two AAA batteries to get you started.

Magnet - ceramic

rectangle, 3/16 inch thick

Your basic refrigerator magnet, about the width and length of a large postage stamp, with N and S poles on each face and a hole in the middle. A useful and popular science supply used in may TOPS titles. Purchase at least 2 per student.


4x6 inch clear, reflecting plastic

A handy scientific tool. It is made of shatter-proof plastic with peel-off protective film. The plane surface may be flexed for funny faces and interesting experiments. Needed in #17 Light, #42 Focus Pocus.

Nails - 3 1/2 inch

steel carpenter's flat-head nail, 16-penny

A specialty item supporting #42 Focus Pocus and #20 Magnetism.

Paper Clips

size #1, steel, box of 100

Paper clips have 1001 uses in TOPS experiments, and science in general. Feel free to use paper clips you already have, but be aware that different brands come in different sizes and weights. In experiments where uniformity is important, don't mix brands.

Rubber Bands - assorted

10 grams each of thin, medium and thick

You get 30 grams of soft, strong, durable rubber bands: thin #16 (about 50), medium #32 (about 20), and heavy-duty #64 (about 10). These sizes are specifically selected to work in most TOPS experiments.

Straight Pins

steel, one and 1/16 inch long

Used in many TOPS experiments. Sometimes required for their magnetic properties. Don't purchase aluminum straight pins by mistake.

Straws - straight

plastic, thin

Any length straw, between 0.20 and 0.25 inches in diameter is suitable. Grocery stores generally carry straws with flexible "elbows." You can use those if you cut off the bendable section before using.

Tape - clear

3/4 inch x 1000 inch roll

Your standard desk tape with matte write-on surface.

Tape - masking

3/4 inch x 55 yd roll

A handy science supply used in most TOPS modules.


light duty, 25 yd spool

Just plain old thread. Used in many TOPS titles, especially in Pendulums #34.

Wire - 24 gauge copper

bare wire

This science lab staple is used in #19 Electricity, #20 Magnetism and #33 Magnetism.

Wire - wrapping

100 feet, plastic insulated

Also called magnet wire or bell wire. This science-lab staple is used in #19 Electricity, #20 Magnetism, #33 Magnetism, and #91 Global TOPS.

Wrapping wire may be recycled from old motors or transformers. If insulated with paint rather than plastic tubing, end leads will need to be sandpapered clean, not stripped with pliers.

Wire - very thin copper

bare wire

The thinner the better. Old household appliance cords may be braided into suitably thin strands. Nip the insulation with wire stripping pliers, then pull off the insulation to inspect. This is a speciality item for #20 Magnetism and #33 Magnetism.

Teaching Tips for #20 Magnetism:

We encourage improvisation - it's one of the main goals of our hands-on approach! You and your students might invent a simpler, sturdier or more accurate system; might ask a better question; might design a better extension. Hooray for ingenuity! When this occurs, we'd love to hear about it and share it with other educators. Please send ideas and photos to

Lesson by Lesson Objectives for #20 Magnetism:

  1. Lesson 1: To identify and label magnetic poles. To observe how magnets characteristically interact with each other, and with a variety of classroom objects.
  2. Lesson 2: To establish a stable, repelling force field between magnets. To study its properties.
  3. Lesson 3: To construct a pin compass. To observe how it can be magnetized and remagnetized to assume different orientations in Earth's magnetic field.
  4. Lesson 4: To define and measure the angle of declination for various geographic locations. To understand that Earth's magnetic poles are paired with unlike geographic poles.
  5. Lesson 5: To correctly identify the poles that form at the ends of a pin when it is touched to a permanent magnet. To link together a long chain of pins, by selectively magnetizing the poles of each one.
  6. Lesson 6: To understand the role of magnetic domains in creating a magnetic field. To predict how dividing or heating these domains affects the field overall.
  7. Lesson 7: To induce magnetic domains in a pin to align, realign, or randomize, producing various magnetic effects.
  8. Lesson 8: To learn to map the lines of force surrounding a magnet with a magnetized pin.
  9. Lesson 9: To map the field of a magnet within a different 2-dimensional plane. To describe the properties characteristic of lines of force.
  10. Lesson 10: To finish mapping the blank areas on each index card force field. To understand lines of force as having direction.
  11. Lesson 11: To understand the 3-dimensional nature of a magnetic force field.
  12. Lesson 12: To map the lines of force between attracting and repelling force fields.
  13. Lesson 13: To correctly model the relative positions of Earth's magnetic and geographic poles on the surface of a crumpled paper bag "planet."
  14. Lesson 14: To explore the shape of an Earth-like magnetosphere.
  15. Lesson 15: To create a magnetic field by sending electricity through a wire coil. To understand how to turn this field on and off, and change its polarity.
  16. Lesson 16: To investigate the lines of force associated with electricity flowing through a coil.
  17. Lesson 17: To improvise a galvanometer that tilts in response to an electromagnetic field. To rewire it into an automatic rocker.
  18. Lesson 18: To build and operate an electromagnet with a removable solenoid.
  19. Lesson 19: To investigate the electromagnetic properties of a solenoid.
  20. Lesson 20: To build a working model of a telegraph receiver and key. To understand how it works.
  21. Lesson 21: To construct a solenoid buzzer. To use a similar design to convert a telegraph into a buzzer.
  22. Lesson 22: To build a motor that spins by turning itself on and off.
  23. Lesson 23: To begin construction of a reverse-poles motor.
  24. Lesson 24: To complete construction of the reverse-poles motor. To understand how it operates.
  25. Lesson 25: To construct a relay circuit that activates a second circuit. To understand how it works.
  26. Lesson 26: To generate electricity within an electromagnet by inducing change within the magnetic field of its iron core. To understand the difference between a motor and a generator.
  27. Lesson 27: To develop a qualitative sense of the relationship between force and distance in a magnetic field. To prepare for a quantitative exploration of the inverse square law.
  28. Lesson 28: To graph how the force of repulsion between two magnetic poles increases as the distance between them decreases. To confirm the inverse square law.

National Science Education Standards (NRC 1996) for #20 Magnetism:

TEACHING Standards

These 28 Task Cards promote excellence in science teaching by these NSES criteria:
Teachers of science...
A: ...plan an inquiry-based science program. (p. 30)
B: and facilitate learning. (p. 32)
C: ...engage in ongoing assessment of their teaching and of student learning. (p. 37)
D: and manage learning environments that provide students with the time, space, and resources needed for learning science. (p. 43)

CONTENT Standards

These 28 Task Cards contain fundamental content as defined by these NSES guidelines (p. 109).
• Represent a central event or phenomenon in the natural world.
• Represent a central scientific idea and organizing principle.
• Have rich explanatory power.
• Guide fruitful investigations.
• Apply to situations and contexts common to everyday experiences.
• Can be linked to meaningful learning experiences.
• Are developmentally appropriate for students at the grade level specified.

Unifying Concepts and Processes

NSES Framework: Systems, order, and organization • Evidence, models and explanation • Constancy, change, and measurement • Evolution and equilibrium • Form and function
Core Concepts/Processes: Change in a magnetic field induces electricity, and change in an electric field induces magnetism. • A magnetic field has both forces inversely proportional to distance from the magnet and direction. • The strength of a magnet increases with alignment of its magnetic domains.

Science as Inquiry (content standard A)

NSES Framework: Identify questions that can be answered through scientific investigations. • Design and conduct a scientific investigation. • Use appropriate tools and techniques to gather, analyze, and interpret data. • Develop descriptions, explanations, predictions, and models using evidence. • Think critically and logically to connect evidence and explanations. • Communicate scientific procedures and explanations. • Use mathematics in all aspects of scientific inquiry.
Core Inquiries: Inquire into energy transfers: Generate electrical energy with mechanical energy. Do the reverse with a motor.

Physical Science (content standard B)

NSES Framework:Magnetism • Properties and changes of properties in matter • Motions and forces • Structure and properties of matter • Interactions of energy and matter
Core Content:Permanent magnets • Temporary Magnets • Lines of force • Magnetic domains • Angle of declination • Electromagnets • Solenoids • Telegraphs • Buzzers • Motors • Generators • Relay switches • Inverse square law

Science and Technology (content standard E)

NSES Framework: Abilities of technological design • Understanding about science and technology
Core Content: Construct solenoids, telegraphs, buzzers, motors, generators, and relay switches.

History and Nature of Science (content standard G)

NSES Framework: Science as a human endeavor • History of science
Core Content: Hans Christian Orsted (1777-1851) discovers electromagnetism.