Magnets are pretty much everywhere. The front of your refrigerator, motors, and inside toys and games. Raven stickers for your car. Sticky Stones.
These magnetic stones are actually polished, magnetized pieces of the mineral hematite. “Don’t be fooled by these seemingly normal stones; they’re magnetic! Build fun structures and explore the theory of magnetism with these unusual and entertaining stones. Rock on! Shapes and sizes may vary.”
Students used a Sticky Stone to magnetize a straight pin by rubbing the stone along the length of the pin, always in the same direction, many times. The pin was then floated on a small square of paper towel in a cup of water. The pin pointed North. No matter which way students turned the pin, it always came back around to point north. Students got to keep their Sticky Stone. Please help your student find a safe place to keep their science souvenirs. We discussed the safety issue of keeping magnets away from pets and younger siblings.
Next, students learned how a navigational compass works. The compass dial has NESW printed on it at 12, 3, 6, and 9 o’clock. There’s a small pointer with a blue end always pointing the same direction. The blue end of the compass pointer pointed the same direction as the straight pin from first lesson. A number of students knew about the north pole of the earth. Some students wondered whythe compass needle pointed towards the north pole of the earth. Factoid: the compass was invented by the Chinese about 2000 years ago.
In a subsequent lesson, we examined how two magnets attract and repel, even though we couldn’t see anything going on between them. Students placed a large magnet under a sheet of paper. Ask them about those cow magnets! They sprinkled iron filings on top of the paper. The tiny bits of iron oriented themselves along the magnetic field lines, now made visible. So there’s this magnetic force field that our eyes can’t see.
In another experiment, students measured how much force was required to pull apart two magnets using a spring scale. Next, they measured how much force was required to pull apart 2 pairs of magnets, and finally, how much force was required to separate 2 triplets of magnets. Each time they predicted the force required before making the measurements. For most students, their predictions got better each time because they had more data, more knowledge from which to predict.