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Teacher’s notes

• About the Science IS activities

Integrated strands

Science concept

• A magnetic field is affected as it passes through different materials.

Nature of Science Theme

Scientists design investigations to test their predictions…

When designing fair tests, scientists change only one variable at a time.

DSSA Investigation Focus

Students’ investigations have the potential to be reconsidered, debated and developed further…

Students can discuss and improve the way they do fair tests to make sure that only one variable is changed.

Activity

Activity sequence

This activity is the second in a sequence of three activities. The first activity is Magnets (1/3): what do magnets attract? The third activity is Magnets (3/3): what patterns can a magnetic field make?

What you need

For each research group (four students per group):

• A bar magnet (the stronger the better).
• Aproximately ten paper clips.
• A range of sheets of different materials of varying thickness, including: paper, card, wood, plastic, glass, aluminium, steel, and a beaker of water (fill to approx. 5mm).
• A range of sheets of different materials of uniform thickness (approx. 2mm), including: a stack of paper, card, wood, plastic, glass, aluminium, and steel.
• Investigation record sheets.

Note: Supporting activity resources are provided below.

Focus

• What is a magnetic field?
• Can magnetic fields pass through air? What about through solid and liquid materials?
• What could we do to find out how different materials affect a magnetic field?
• How do scientists know what other scientists think about an idea?
• How important is it that science ideas get discussed and debated?
• What determines if an investigation is ‘fair’?
• What could researchers do if they recognised weaknesses or limitations in their own investigations, or other scientists’ investigations?

Exploration

1. Divide the class into research teams, with four students per team.
2. Explain that each research team will test a range of materials. By placing the material between the magnet and the paper clips, the students will test how the material affects the ability of the magnet to attract paper clips (demonstrate with paper).
3. Ask the students to record their predictions on Investigation record sheet 1 as to whether they think each material of varying thickness will affect the strength of the magnetic field, and how they think each material will affect the strength of the magnetic field.
4. Issue the magnets, paper clips, and materials of varying thickness to the students.
5. When the investigation is completed, collect the equipment (this removes the temptation to fiddle). Ask each research team to report what they did and what they found out.
6. Ask, “Is it fair if the thickness of the material is not the same?” Explain to the students that the aim is to repeat the investigation to make it even more ‘fair’ than before. Ask the students to repeat their investigation using different materials of uniform thickness. Students record their predictions and observations on Investigation record sheet 2.

Extension

• Ask students to undertake a library or Internet search on William Gilbert (1540–1603), who developed an investigation on magnetism that was an early example of a fair test.
• Get students to test what other materials magnetism can pass through, including glass and various liquids.
• Ask students how the strength of the magnetic field could be measured.

Reflection

• Do you think your second investigation was more ‘fair’ than your first investigation? Why?
• What factors are needed for an investigation to be determined ‘fair’?
• How useful was reporting back to the class? Did you learn anything from other groups? Do you think your comments helped any other groups? What opportunities do you think scientists have to look at each other’s work?