Two Tries, One Problem
A 45-minute Kindergarten lesson on comparing test results from two designs made for the same problem.
Two Tries, One Problem is a free 45-minute Kindergarten to Grade 2 science lesson plan for Common Core standard K-2-ETS1-3 — test two designs for the same problem and compare how each performs. 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:
- Kindergarten to Grade 2
- Length:
- 45 minutes
- Standard:
- K-2-ETS1-3
Kindergarten to Grade 2 · Engineering Design
K-2-ETS1-3
Analyze data from tests of two objects designed to solve the same problem to compare the strengths and weaknesses of how each performs.
Objective
Students will be able to compare two designs on their results and name a strength of each.
Students are successful when they can
- Says which design did the job better.
- Names one good thing about the other one.
- Uses the results rather than a preference.
What you need
- The two ramps and the car from the earlier lesson
- A two-column results chart
- The printable practice sheet linked at the end of this plan
The lesson
Warm-up — both did something right
5 min- Show the two-ramps record: A sent the car 4 steps, B sent it 9.
- Ask which is better, then say the class will come back to that.
Teach — strengths on both sides
12 min- Fill the first column for ramp B: sent the car furthest, 9 steps.
- Fill the first column for ramp A: easy to build, did not fall over.
- Ask which one you would choose to send the car far. Ramp B.
- Ask which one you would choose with two minutes to build. Ramp A.
- Say the point: better depends on the job, and each design has a strength.
- Ask what the record does not tell you: how long each took to build.
“Better at what? Say the job first.”
Investigate — test two of your own
15 min- Groups build two catchers for a rolling ball: a box and a folded card.
- They roll the ball at each one five times and tally the catches.
- They fill a two-column chart with a strength of each.
- They name which they would use, and for what job.
Independent practice
10 min- Students complete the 'Two Tries, One Problem' page.
- Check the answer quotes a number from the record.
Close
3 min- Ask each group for one thing they would change about the losing design.
What goes wrong, and why
Each of these is a reasoning error rather than carelessness. The fix addresses the reasoning.
Declares one design simply best.
Why: One number was bigger.
Fix: Best at what? Ramp A was easier to build and stayed up.
Compares two designs that were tested differently.
Why: Both were tested, so both count.
Fix: Same car, same start. Otherwise the results are not comparable.
Names a strength with no evidence.
Why: It looked sturdier.
Fix: Point at the tally. A strength you cannot point at is a guess.
If they are not there yet
- One strength each rather than two.
- A chart with the first row filled in.
If they finish early
- Combine the best part of each design into a third.
- Say what extra test would settle which is better.
- Find a job where the losing design would win.
Exit ticket
Ramp A sent the car 4 steps and was easy to build. Ramp B sent it 9 steps and fell over twice. Which would you use, and for what job?
What to look for: Either, with the job named and a number quoted. A choice with no job stated means the better-at-what idea needs another run.
Printable practice for K-2-ETS1-3
Free to print and copy, answer key included. Each sheet can generate a fresh set of problems for a retake.
- Two Tries, One ProblemRead the record, then answer the questions.
Questions about Two Tries, One Problem
How long does the Two Tries, One Problem lesson take?
45 minutes, split across 5 timed sections: warm-up 5 min, teach 12 min, investigate 15 min, independent practice 10 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 Two Tries, One Problem teach?
K-2-ETS1-3 — K-2-ETS1-3, Engineering Design for Kindergarten to Grade 2: “Analyze data from tests of two objects designed to solve the same problem to compare the strengths and weaknesses of how each performs.” In plain terms, test two designs for the same problem and compare how each performs.
What do I need to teach this lesson?
The two ramps and the car from the earlier lesson, a two-column results chart 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: declares one design simply best; compares two designs that were tested differently and names a strength with no evidence. 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: “Ramp A sent the car 4 steps and was easy to build. Ramp B sent it 9 steps and fell over twice. Which would you use, and for what job?.” Either, with the job named and a number quoted. A choice with no job stated means the better-at-what 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 Two Tries, One Problem?
Yes — 1 printable K-2-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 Two Tries, One Problem 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 K-2-ETS1-3 of the Next Generation Science Standards.