Measuring a Magnetic Field Science Experiment

This 3rd grade magnetic field experiment for kids is a fun and simple hands-on activity to get students to think like scientists. All you need are a few materials and you’ll be able have your third grade students engaged and thinking critically! The PowerPoint lessons and student lab sheet I use are part of this third grade Force & Motion science unit.

My students absolutely love learning about magnets and magnetism. This science concept lends itself to easy hands-on activities since students are able to feel the magnetic pull on certain objects.

Measuring a magnetic field experiment

In this experiment, students measure a magnetic field. Then they will draw and label a diagram showing the magnetic field.

Before I get my students started on the experiment, we have several lessons on forces, including one on magnetic force.

What is a magnet?

A magnet is an object that can pull certain types of metal toward itself. The force of magnets is called magnetism. It is an invisible force caused by the electrons in the matter that makes up everything around us. A magnet has a magnetic field and attracts or repels other objects.

What is a magnetic field?

A magnetic field is the area around a magnet where there is a magnetic force. The shape of the magnetic field depends on the shape of the magnet. Magnetic fields are invisible, but students will be able to feel the pull of the magnetic force using magnets and paperclips.

I use this magnetic field science experiment to get students to think critically about planning and carrying out an investigation to answer a question. Students design their own procedure to measure a magnetic field and create a diagram to show the magnetic field.

Discuss Earth’s magnetic field

My students are always fascinated to discover the fact that the Earth is like a giant magnet, so there is a magnetic field all around us. The North Pole and the South Pole are really just the poles of Earth’s magnet. The magnetic field is strongest at these two poles.

Introduce the lab by posing the question: “How can you measure a magnetic field?”

How can you measure a magnetic field?

Materials:

bar magnet
paperclip
yarn
ruler
craft stick
lab sheet

Place students in small groups or with science partners with the materials needed to carry out the experiment. Then guide students through the following procedure.

Procedure:

1. Tape a bar magnet to a craft stick. Tie 6 inches of yarn to a large paperclip. Place the paperclip on the magnet and gently pull to get a feel for the pull of the magnet on the paperclip.

2. Holding the paperclip at the knot, slowly move it toward the magnet until it enters the magnetic field space and stands up. This will take several tries to get a feel for where the magnetic field starts.

3. While the magnet is pulling the paperclip, slowly and carefully move your grip on the yarn down. This part is tricky and took my students a few tries to find just how far from the magnet they could pull the paperclip before the magnet “let go” and the paperclip moved outside of the magnet’s pull.

4. Next, a partner holds a ruler near the craft stick to measure the length of the magnetic field. The magnetic field is the space between the stick and the paperclip.

5. Finally, students draw their magnet, using arrows to label the magnetic field. They will label their drawing with the measurements. Then they will answer the questions on their lab sheet.

Wrap up the experiment by asking students: In what situation would someone need to know the size of a magnetic field? How do you think the size of a magnet relates to the size or length of its magnetic field.

More Force & Motion experiments and lesson plans

This measuring a magnetic field experiment is an exciting and hands-on way for students to explore magnets and magnetism. It’s part of a complete NGSS Force & Motion unit for 3rd grade that is also available in a digital version with audio narrated lesson slides.