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Teacher’s notes

• About the Science IS activities

Integrated strands

Science concept

• Only a few materials (and not all metals) are attracted to magnets.

Nature of Science Theme

Scientists’ predictions are based on their existing science knowledge…

Scientists' expectations about the results of an investigation are based on what they already know.

DSSA Investigation Focus

Students’ investigations may have unexpected results…

Students' observations may contradict their previous experience and understanding of phenomena.

Activity

Activity sequence

This activity is the first in a sequence of three activities. The second activity is Magnets (2/3): what can magnetism pass through? The third activity is Magnets (3/3): what patterns can a magnetic field make?

What you need

• A tray (for materials) for each group.
• A set of bar magnets (the stronger the better) – enough for one magnet per group of students.
• Sets of materials as listed – enough for one set per group of students:
  • steel and iron (a number of different steel or iron items, e.g. nails, bolts, ‘tin’ can lid, cast iron, iron sand, rust)
  • copper
  • aluminium (extrusions or drink cans)
  • zinc or lead
  • nickel (see local secondary chemistry department)
  • glass
  • plastics (various)
  • ceramics
  • wood
  • cardboard.
• Investigation record sheet.
• Access to Internet terminals.

Note: Supporting activity resources are provided below.

Focus

• Imagine a scenario where you have been contracted to research how to separate materials at a recycling station.
• What sorts of materials can magnets attract?
• Is there anything magnets can’t attract?
• Do magnets ever repel materials?
• When setting up investigations, what do scientists base their predictions on?
• What do scientists do when their investigations don’t give the expected results?

Exploration

1. Divide the class into groups and give each group a tray of materials. Ask them to choose five materials in their tray to investigate and to list them on the investigation record sheet.
2. Ask students in their groups to discuss each item and decide (a) what it is made of, and (b) whether they think it will be attracted to a magnet. Ask the students to record their predictions in the investigation record sheet.
3. Issue the sets of items and magnets and ask the student groups to try each item to see if it is attracted to the magnet. Ask the students to record their observations in the investigation record sheet.
4. As a class, collate the observations and identify any unpredicted results. Classify the items into those that appear to be affected by magnets, and those that don’t.
5. Consider the collated observations and look for what the attracted items have in common (e.g. iron compared to steel).
6. Return to the original question, “What sorts of materials can magnets attract?” Ask, “Do magnets only appear to affect things made of iron?”

Extension

• Try using a magnet to separate a pile of different small objects (some are steel or iron).
• See if you can find a way to get the magnet to release the iron once it has picked it up out of the pile.

Reflection

• What sort of materials do magnets appear to attract?
• What sort of materials do magnets appear to not attract?
• How can you explain the difference between materials that appear to be attracted by magnets, and those that don’t appear to be attracted by magnets?
• What did you base your original predictions on? How do you think scientists make predictions for their investigations?
• How did you deal with results that were different from what you expected? How do you think scientists might deal with the same issue?