Testing tells you the truth. Every result — pass or fail — is information. And information makes your next design better!
📋 NGSS Standard: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.
🎯 Learning Objectives
By the end of this lesson, students will be able to:
Test their bridge against specific, measurable criteria
Record test results accurately in a data table
Redesign based on what the data shows
🔬 The Big Idea
In Lesson 4, you built your bridge and took a quick look at how it worked. Today, we get serious about testing. Real engineers define exact criteria — the rules a design must pass — and then test their design against those rules. Results are recorded, not just remembered. Then the magic happens: we use the data to make a better design!
📋 Official Bridge Test Criteria
🌉 Your Bridge Must Pass ALL 3 Tests:
1 The toy car or marble must cross the bridge completely from one side to the other.
2 The bridge must NOT touch the water at any point during or after the crossing.
3 The bridge must hold its shape for 10 seconds after the car crosses (no collapsing!).
💡 Key vocabulary: criteria, test, data, record, redesign, iterate, version
📦 Materials
🌉 For Testing and Rebuilding
Your bridge from Lesson 4 (or rebuild it quickly if it was taken apart)
3–5 additional sheets of plain paper (for the redesign)
Additional tape (6–12 more inches)
Additional toothpicks (5–8)
Toy car or marble
Puddle tray with water
Timer (phone timer works great)
Student worksheet (last pages of this lesson)
🔬 Let's Get Started
Step 1 — Official Test: Version 1 Bridge (5 min)
Run the official test on your Lesson 4 bridge. For each criterion:
Test it clearly
Record the result: ✅ Pass or ❌ Fail
If it failed: write down WHY and what seemed to cause the problem
Be honest! If your bridge barely passed or the car almost fell in — record that too.
Step 2 — Analyze: What Needs to Improve? (5 min)
Look at your test results. Ask:
Which test(s) failed? Why did they fail?
What part of the bridge caused the problem?
What one change would most likely fix the biggest problem?
Write your answers on the worksheet before touching the bridge.
Step 3 — Redesign: Plan Version 2 (5 min)
Draw a quick sketch of your Version 2 design. What's different from Version 1? Focus on the ONE most important change first — don't try to fix everything at once! Mark what's changing and WHY.
Step 4 — Build Version 2 (10 min)
Build the improved bridge. You can use the old bridge as a starting point (modify it) or start fresh — whichever makes more sense based on your redesign plan.
Step 5 — Official Test: Version 2 (5 min)
Run the SAME 3-part official test on your Version 2 bridge. Record results. Compare:
Did Version 2 pass more tests than Version 1? ✅
Did anything get worse? (This happens sometimes — good to know!)
What would Version 3 fix? (Even if you don't build it)
Version 2 is always better than Version 1 — because Version 2 uses real information from the test, not just a guess. Celebrate the redesign! Getting to Version 2 is a real achievement.
💬 Discussion Questions
🗣️ "Failing Forward" Discussion
Question:"In engineering, a test that shows your design DOESN'T work is called a 'failure.' But is it really a failure?"
→ Not at all! Every failed test tells you something important — what doesn't work, and why. Engineers call this "failing forward." A test that fails isn't wasted time — it's data you couldn't get any other way.
Real examples:
The Wright Brothers' first attempts at flying didn't work — but each attempt taught them something that made the next attempt better. Eventually, they flew!
Thomas Edison said he didn't fail 1,000 times making the lightbulb — he found 1,000 ways that didn't work. Each "failure" got him closer to the one way that DID work.
→ The question isn't "Did it work?" but "What did I learn?" A test that teaches you something is NEVER a failure.
🗣️ More to explore:
Why is it important to test against specific criteria instead of just seeing how it goes?
What would happen if engineers stopped after Version 1, even if it barely worked?
Can you think of something you've gotten better at through practice? Is that like engineering iteration?
🌟 What Real Engineers Know
The smartphone in your pocket went through thousands of test cycles before it reached you. Every app, every material, every curve was tested, failed, analyzed, and improved. What you hold is not Version 1 — it's Version 1,000. Engineering is patience + curiosity + willingness to try again. You're doing it right now.
🚀 Extensions
⚖️ Load Test: How much weight can your bridge hold? Add pennies one at a time to the bridge until it collapses. Record how many it held.
🌧️ Weather Test: What if it rained? Gently drip water on the bridge from above. Does it still hold?
🏗️ Version 3: Based on Version 2 results, what would Version 3 look like? Draw it — even if you don't build it yet.
📊 Bar Graph: Make a simple bar chart showing how many tests each version passed (out of 3). Visualizing data is a real science skill!
👩🏫 Parent/Teacher Notes
Enforce the "one change at a time" rule: When redesigning, students often want to change everything. Coach them to pick the single most important change. This isolates variables — a key scientific thinking skill.
Be specific about "why it failed": "It fell in" is not specific enough. Coach: "Why did it fall in? Which part? What made that part weak?"
The "failing forward" discussion is critical: Many kids have been taught that failure is shameful. Explicitly reversing this framing — with the Wright Brothers and Edison examples — is one of the most important mindset lessons of this unit.
Assessment: Did students record data from BOTH version tests? Can they explain what changed between versions and WHY? Can they articulate what a "Version 3" might fix? That's success for Lesson 5.
