What you'll need
- Chart paper and felt pens
- Enameled wire
- Dry cell batteries and holders
- Iron nails
- Insulated alligator clips
- Steel paper clips
- "Build an electromagnet" worksheet for each student
- "Build an electromagnet competencies self-assessment" for each student
If you can, try constructing your own electromagnet beforehand so you understand how it’s done.
- Metal components in the circuit you are building will get warm during the activity, so don’t touch the batteries, alligator clips, coil, or paper clips.
- When connecting and disconnecting the wires from the batteries, only touch the rubber parts of the alligator clips.
- Disconnect the circuit every two minutes to allow it to cool down.
Creating a friendly and fair competition
- Part of this activity involves your students competing to see who can create the strongest electromagnet. This is a perfect opportunity to introduce the idea of variables and how they can impact an experiment.
- Ask your class how they might go about making sure that a free throw contest in basketball is fair. How would they make sure that no competitor has an unfair advantage?
- This can be done by using the same ball and shooting at the same hoop and from the same line.
- All of the things that can be different in an activity are called “variables” and in science the objective is to control all of those variables.
Building the electromagnets
- Students will work individually to create an electromagnet. They should complete the "Build an electromagnet" worksheet as they follow the below steps.
- Wrap the wire tightly around the nail to create a coil, leaving 6 cm of wire sticking out at each end of the nail.
- Use the sandpaper to scrape away the enamel coating at both ends, exposing about 2 cm of copper wire.
- Connect the ends of the coil to the battery using the insulated alligator clips.
- Place the electromagnet close to the edge of the table or desk so the nail hangs over the edge. Then hold one of the steel paper clips close to the nail.
- Continue to hold paper clips close to the nail and, using the chart paper and felt pens, keep track of how many paper clips each student's electromagnet is able to hold up.
Hypotheses and testing the electromagnets
- Gather the students and talk about different ways they could increase the number of paper clips their electromagnet can hold.
- On their worksheet, have your students write a hypothesis on how to make a stronger electromagnet. Encourage them to write their hypotheses using “if, then” statements.
- Have students test their hypotheses by changing something about their electromagnet and seeing how many paper clips it can hold. Ensure that they are filling in their worksheets as they test.
Document and debrief
- Bring the class together again and have students share their hypotheses and the results of their testing. Challenge them to think about other variables they might like to test.
Modify or extend this activity
Have your students explore other variables that can affect the strength of an electromagnet by using materials brought from home or found elsewhere in the school.