A Job for a Magnet
A 55-minute Grade 3 lesson on defining a simple design problem that could be solved by applying what you know about magnets.
A Job for a Magnet is a free 55-minute Grade 3 science lesson plan for Common Core standard 3-PS2-4 — define a problem that magnets could solve. It is timed across 5 sections, gives the exact wording to use where the wording carries the mathematics, names 3 misconceptions with the teaching move that addresses each, and ends with an exit ticket and a printable worksheet with its answer key.
- Grade:
- Grade 3
- Length:
- 55 minutes
- Standard:
- 3-PS2-4
Grade 3 · Physical Science
3-PS2-4
Define a simple design problem that can be solved by applying scientific ideas about magnets.
Objective
Students will be able to define a problem that magnets could solve and say why magnets suit it.
Students are successful when they can
- States the problem before the solution.
- Says which magnetic property it uses.
- Rejects a problem magnets cannot solve.
What you need
- Magnets of several kinds, steel and non-steel objects
- Problem cards from around the school
- The printable practice sheet linked at the end of this plan
The lesson
Warm-up
5 min- Show a tin of mixed steel pins and plastic beads.
- Ask how the pins could be got out quickly.
Teach — problem first, then the property
14 min- Write the problem: how to separate steel pins from plastic beads.
- Name the property used: magnets attract steel and not plastic.
- Do a second: a door that swings open, solved by a magnetic catch.
- Do one magnets cannot solve: how to stop the room being noisy.
- Ask why not: nothing in it is steel and nothing needs holding.
- Say the test: name the problem, then name the magnetic property that fits it.
“Which property of a magnet does this problem actually need?”
Investigate — find three problems
19 min- Groups walk the classroom looking for problems magnets could solve.
- For each they write the problem and the property it uses.
- They test one with a real magnet and record whether it worked.
- They find one problem magnets cannot solve and say why.
Independent practice
14 min- Students complete the 'A Job for a Magnet' page.
- Check the match uses a magnetic property, not just the word magnet.
Close
3 min- Choose the class's best magnet problem to design for next.
What goes wrong, and why
Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.
Assumes magnets attract all metals.
Why: They attract many familiar ones.
Fix: Test aluminium and copper. Neither responds.
Writes a solution as the problem.
Why: 'Use a magnet' feels like the answer.
Fix: The problem is what goes wrong. The magnet is the solution to it.
Picks a problem with nothing steel in it.
Why: Magnets are the topic.
Fix: Ask what the magnet would act on. If nothing, the problem does not fit.
If they are not there yet
- Three problem cards to sort into fits and does not fit.
- The property named on the back of each card.
If they finish early
- Design a magnetic solution and test it.
- Find a problem two different magnet properties could solve.
- Say why a magnetic catch is better than a hook here.
Exit ticket
Steel pins are mixed into a sand tray. State the problem and the magnetic property that solves it.
What to look for: How to get the steel pins out of the sand, using that magnets attract steel and not sand. Naming only 'use a magnet' means the problem step is missing.
Printable practice for 3-PS2-4
Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.
- A Job for a MagnetDraw a line from each problem to the magnet solution.
Questions about A Job for a Magnet
How long does the A Job for a Magnet lesson take?
55 minutes, split across 5 timed sections: warm-up 5 min, teach 14 min, investigate 19 min, independent practice 14 min, close 3 min. The minutes are stated per section and add up to the stated length, so the plan can be cut or extended at a section boundary rather than abandoned halfway.
Which standard does A Job for a Magnet teach?
3-PS2-4 — 3-PS2-4, Physical Science for Grade 3: “Define a simple design problem that can be solved by applying scientific ideas about magnets.” In plain terms, define a problem that magnets could solve.
What do I need to teach this lesson?
Magnets of several kinds, steel and non-steel objects, problem cards from around the school and the printable practice sheet linked at the end of this plan. Everything listed is either ordinary classroom equipment or a free printable from this site — there is nothing to buy and nothing to prepare beyond photocopying.
What mistakes should I expect in this lesson?
Three, each a reasoning error rather than carelessness: assumes magnets attract all metals; writes a solution as the problem and picks a problem with nothing steel in it. The plan gives the thinking behind each one and the teaching move that addresses the thinking rather than the symptom.
How do I know whether the lesson worked?
The exit ticket asks: “Steel pins are mixed into a sand tray. State the problem and the magnetic property that solves it.” How to get the steel pins out of the sand, using that magnets attract steel and not sand. Naming only 'use a magnet' means the problem step is missing. That tells you whether the class needs a reteach or a thirty-second conversation before you plan tomorrow.
Is there a worksheet to go with A Job for a Magnet?
Yes — 1 printable 3-PS2-4 worksheet, linked at the end of the plan and free like the rest of the site. Each one comes with an answer key and 25 versions, so the practice after the lesson can be a different paper on every desk.
Is A Job for a Magnet free to use?
Yes. The plan, its printables and their answer keys are free to read, print and photocopy for your own class, with no account and no email capture. It was last reviewed on 8 September 2026. Please do not resell it or republish it as your own.
Last reviewed 2026-09-08. Aligned to 3-PS2-4 of the Next Generation Science Standards.