When Things Collide
A 55-minute Grade 4 lesson on asking questions and predicting what happens to energy when objects collide.
When Things Collide is a free 55-minute Grade 4 science lesson plan for Common Core standard 4-PS3-3 — ask and predict what happens to energy when objects collide. 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 4
- Length:
- 55 minutes
- Standard:
- 4-PS3-3
Grade 4 · Physical Science
4-PS3-3
Ask questions and predict outcomes about the changes in energy that occur when objects collide.
Objective
Students will be able to predict a collision outcome and explain it as a transfer of energy.
Students are successful when they can
- Predicts before the collision.
- Measures what the struck object does.
- Explains the outcome as energy transferred.
What you need
- A grooved track, two identical marbles, a metre rule
- A results table with release height and distance travelled
- The printable practice sheet linked at the end of this plan
The lesson
Warm-up
5 min- Roll one marble into a still one and ask the class what will happen to each.
- Take predictions before running it.
Teach — where did the movement come from?
14 min- Release from 5 cm. The striker nearly stops; the struck marble rolls 6 cm.
- Ask where the struck marble's movement came from.
- Repeat from 10 and 15 cm and record both marbles each time.
- State the pattern: a faster striker sends the struck marble further.
- Ask about the click: some energy left as sound.
- Say why the struck marble must start still: any movement afterwards came from the collision.
“It was still. So where did that movement come from?”
Investigate — three heights, predictions first
19 min- Groups predict the struck marble's distance for three release heights.
- They run each three times and record all results.
- They compare predictions with measurements.
- They write one question their results raise but do not answer.
Independent practice
14 min- Students complete the 'When Things Collide' page.
- Check answers explain rather than only describe.
Close
3 min- Ask what happens to the energy in a collision where both marbles stop.
What goes wrong, and why
Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.
Says the energy disappeared when the striker stopped.
Why: It stopped moving.
Fix: Look at the struck marble. It went somewhere.
Ignores the sound and heat.
Why: They are hard to see.
Fix: The click is energy leaving. That is why the struck marble gets less than everything.
Predicts after seeing the result.
Why: The result is right there.
Fix: Write the prediction first. A prediction after the fact tests nothing.
If they are not there yet
- Two heights and one run each.
- A prediction frame with an example.
If they finish early
- Try a heavier striker and predict what changes.
- Explain a head-on collision where both stop.
- Design a test for how much energy the click carries away.
Exit ticket
A marble is rolled into a still marble and stops. The struck marble rolls 13 cm. What happened to the energy?
What to look for: It was transferred to the struck marble, with some lost as sound and heat. 'It disappeared' means the transfer idea needs another run.
Printable practice for 4-PS3-3
Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.
- When Things CollideRead the record, then answer the questions.
Questions about When Things Collide
How long does the When Things Collide 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 When Things Collide teach?
4-PS3-3 — 4-PS3-3, Physical Science for Grade 4: “Ask questions and predict outcomes about the changes in energy that occur when objects collide.” In plain terms, ask and predict what happens to energy when objects collide.
What do I need to teach this lesson?
A grooved track, two identical marbles, a metre rule, a results table with release height and distance travelled 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: says the energy disappeared when the striker stopped; ignores the sound and heat and predicts after seeing the result. 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 marble is rolled into a still marble and stops. The struck marble rolls 13 cm. What happened to the energy?.” It was transferred to the struck marble, with some lost as sound and heat. 'It disappeared' means the transfer idea needs another run. 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 When Things Collide?
Yes — 1 printable 4-PS3-3 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 When Things Collide 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 4-PS3-3 of the Next Generation Science Standards.