Magnets are capable of attracting through all non-magnetic material. The earth itself is a magnet. The compass acts like it does because the earth has a magnetic north pole and a magnetic south pole. It is possible to magnetize and demagnetize material. Sizes, shapes, and strengths of magnets can vary greatly.
Magnets can be as small as the eye of a needle, or as large as a car.
Magnets come in such shapes as a donut, horseshoe, rectangle, sphere, etc. And don't be deceived a magnet's size is not always relative to its strength. However combining two magnets will increase the strength. It is important to realize that at a first grade level, children need key concept words spelled out in a special place for them. This way you are making sure you've covered all three ways to categorize magnets.