Testing Until It Fails
A 60-minute Grade 5 lesson on running controlled tests to failure and using the failure point to improve a prototype.
Testing Until It Fails is a free 60-minute Grade 3 to Grade 5 science lesson plan for Common Core standard 3-5-ETS1-3 — run fair tests, controlling the variables, to find what to improve. 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 to Grade 5
- Length:
- 60 minutes
- Standard:
- 3-5-ETS1-3
Grade 3 to Grade 5 · Engineering Design
3-5-ETS1-3
Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.
Objective
Students will be able to run a controlled test to failure and improve the point that failed.
Students are successful when they can
- Lists the variables held constant.
- Records where and at what point it failed.
- Improves that point and retests under the same conditions.
What you need
- Prototypes from the design lessons, measured loads or volumes
- A test record with a controls section and a failure-point section
- The printable practice sheet linked at the end of this plan
The lesson
Warm-up
5 min- Test a prototype until it fails and ask what the class learned.
- Press for the location, not just the fact.
Teach — control, escalate, locate
15 min- List the controls before any testing: volume, rate, judging standard.
- Escalate in equal steps and record at each step.
- At failure, record the step AND the place that gave way.
- Improve only that place and retest with the same controls.
- Compare the two failure points and say whether the change worked.
- Say why a design that never fails has not been tested hard enough.
“Where exactly did it give way? Change that and nothing else.”
Investigate — two cycles of test and improve
22 min- Groups test their prototype to failure three times under stated controls.
- They record the failure load and location each time.
- They make one change to the failure point and retest.
- They report whether the failure point moved and what that shows.
Independent practice
15 min- Students complete the 'Testing Until It Fails' page.
- Check controls are listed alongside the result.
Close
3 min- Ask whose failure point moved, and what they would improve next.
What goes wrong, and why
Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.
Stops testing when it passes.
Why: It works.
Fix: Increase the load until it fails. That is where the limit is.
Records only that it failed.
Why: Failure is the event.
Fix: The location is what tells you what to change.
Changes several things at once.
Why: Time is short.
Fix: One change per cycle, or the improvement cannot be attributed.
If they are not there yet
- A controls checklist to tick.
- One test cycle rather than two.
If they finish early
- Predict the new failure load before retesting.
- Find a prototype whose failure point cannot be improved within the constraints.
- Say what test would be unfair however carefully it was run.
Exit ticket
Your filter leaks at the seal in all three tests. Name two controls you kept and what you would change.
What to look for: Controls such as water volume and pour rate, with only the seal changed. A change with no controls listed means the fair-test idea needs another run.
Printable practice for 3-5-ETS1-3
Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.
- Testing Until It FailsCircle the best answer.
Questions about Testing Until It Fails
How long does the Testing Until It Fails lesson take?
60 minutes, split across 5 timed sections: warm-up 5 min, teach 15 min, investigate 22 min, independent practice 15 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 Testing Until It Fails teach?
3-5-ETS1-3 — 3-5-ETS1-3, Engineering Design for Grade 3 to Grade 5: “Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.” In plain terms, run fair tests, controlling the variables, to find what to improve.
What do I need to teach this lesson?
Prototypes from the design lessons, measured loads or volumes, a test record with a controls section and a failure-point section 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: stops testing when it passes; records only that it failed and changes several things 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: “Your filter leaks at the seal in all three tests. Name two controls you kept and what you would change.” Controls such as water volume and pour rate, with only the seal changed. A change with no controls listed means the fair-test 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 Testing Until It Fails?
Yes — 1 printable 3-5-ETS1-3 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 Testing Until It Fails 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 3-5-ETS1-3 of the Next Generation Science Standards.