Acting Across a Gap
A 55-minute Grade 3 lesson on asking cause-and-effect questions about magnets and static acting without contact.
Acting Across a Gap is a free 55-minute Grade 3 science lesson plan for Common Core standard 3-PS2-3 — ask what causes two objects to attract or repel without touching. 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-PS2-3
Grade 3 · Physical Science
3-PS2-3
Ask questions to determine cause and effect relationships of electric or magnetic interactions between two objects not in contact with each other.
Objective
Students will be able to ask and answer a cause-and-effect question about a force acting across a gap.
Students are successful when they can
- Shows an effect with no contact.
- Names what was changed and what happened.
- Asks a question a test could answer.
What you need
- Bar magnets, paperclips, rulers, paper, card, a steel plate
- Balloons and small paper pieces
- The printable practice sheet linked at the end of this plan
The lesson
Warm-up
5 min- Slide a magnet towards a paperclip until the clip jumps.
- Ask what touched the clip. Nothing did.
Teach — change one thing, watch the effect
14 min- Measure the distance at which the clip first moves: 4 cm.
- Put paper between and measure again: still 4 cm.
- Put card between: 3 cm. Put a steel plate: it does not move at all.
- Name the cause and effect each time: what was changed, and what happened.
- Rub a balloon and pick up paper pieces without touching them.
- Turn each observation into a question a test could answer.
“What did you change, and what happened because of it?”
Investigate — distance and barriers
19 min- Groups find the distance at which a clip first moves, three times, and average it.
- They repeat with three different barriers between.
- They record which barriers changed the distance and which stopped it entirely.
- They write two cause-and-effect questions their results answer.
Independent practice
14 min- Students complete the 'Acting Across a Gap' page.
- Check answers name the cause, not just the effect.
Close
3 min- Ask what the steel plate result suggests about how the pull travels.
What goes wrong, and why
Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.
Thinks something invisible physically touches the clip.
Why: Contact is how pushes usually work.
Fix: Stay with the observation: the effect happens across a measured gap.
Thinks all metals are magnetic.
Why: Magnets stick to some metals.
Fix: Try aluminium foil and a copper coin. Neither moves.
Changes distance and barrier at once.
Why: Both are interesting.
Fix: Then no result can be explained. Change one at a time.
If they are not there yet
- One barrier and one distance measurement.
- A results table with headings filled in.
If they finish early
- Find whether two magnets together reach further.
- Test whether a magnet works through water.
- Explain why the steel plate stopped it and paper did not.
Exit ticket
A paperclip moves when a magnet is 4 cm away. What is the cause, the effect, and what does it show?
What to look for: Bringing the magnet nearer causes the clip to move, showing a magnet acts without contact. Naming only the movement means the cause step is missing.
Printable practice for 3-PS2-3
Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.
- Acting Across a GapCircle the best answer.
Questions about Acting Across a Gap
How long does the Acting Across a Gap 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 Acting Across a Gap teach?
3-PS2-3 — 3-PS2-3, Physical Science for Grade 3: “Ask questions to determine cause and effect relationships of electric or magnetic interactions between two objects not in contact with each other.” In plain terms, ask what causes two objects to attract or repel without touching.
What do I need to teach this lesson?
Bar magnets, paperclips, rulers, paper, card, a steel plate, balloons and small paper pieces 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: thinks something invisible physically touches the clip; thinks all metals are magnetic and changes distance and barrier at once. 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: “A paperclip moves when a magnet is 4 cm away. What is the cause, the effect, and what does it show?.” Bringing the magnet nearer causes the clip to move, showing a magnet acts without contact. Naming only the movement means the cause 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 Acting Across a Gap?
Yes — 1 printable 3-PS2-3 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 Acting Across a Gap 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-PS2-3 of the Next Generation Science Standards.