|Magnetized needle pointing towards north.|
While studying magnetism teachers will often introduce Earth’s magnetic field to students with the help of a class set of compasses. Quality compasses can be expensive and unless teachers are planning to have students use them in basic orienteering practice they are unnecessary with the help of some inexpensive materials and a little know-how.
“Create a Compass” is an engaging activity for elementary students that shows 1) How a compass is made and works. 2) Unmagnetic objects made of magnetic material can be made magnetic and 3) Magnetic objects will be influenced by Earth’s magnetic field.
Having at least one compass on hand for students to observe as a grabber at the start of the lesson can be helpful in prodding inquisitive questions from students about how it works and force students to think about the value of the ability to navigate and understand one’s direction. As the introduction to the lesson comes to a close asking students how a compass works will enlighten the teacher as to how many kids are aware of Earth’s magnetic field and who knows that the needle always points “North.” Depending on the responses received from earlier pre-questions teachers may want to dive deeper into the difference between geographic and magnetic north or make cross-curriculum connections with early explorers and the uses of compasses which will not be dived into on this blog.
To build one’s own compass, students will need:
- bar magnet
- sewing needle or pin
- a shallow basin of water (see photograph for an example)
- piece of cork or plastic.
Students must start by first magnetizing the needle. To do this, students must run one end of the bar magnet from one end of the needle to the other over and over (30-50 times should do the trick.) To confirm that the pen is magnetized had students try to pick up a single staple with the needle. After their needle is magnetized students must place the needle on top of the plastic or cork peace and lay it on top of the water poured into the shallow basin.
With no other forces acting on the needle but the Earth’s magnetic field the “south” polarized end of the pin will twist towards the magnetic north pole (opposites attract.) If the bar magnet is placed near the pin the magnetic strength of the bar magnet will override Earth’s magnetic field and the pin will follow the bar magnet.
How a pin can become magnetized is an abstract concept that requires students to have a previous understanding that all objects are made of particles (atoms or molecules to be more scientific.) When an object is made primarily out of atoms of iron, nickel, or cobalt (like in the case of our pin) the atoms physically move and rotate so that they are in alignment with a magnetic field if they come into contact with one strong enough to move them (such as the bar magnet run repetitively over the magnet.) The SMARTBoard file able to be found here is an interactive opportunity for students to take an unmagnetized model of the pin (top) and rotate the particles of the pin in place so that they are all aligned in one direction and magnetized (bottom.)