Building and Testing a Prototype

Engineering — Design Process | Unit 1, Lesson 4 of 6

📚 Grade: 3rd Grade⏱️ Duration: 45–60 minutes🛠️ Subject: Engineering — Design Process

🛠️📏🧪

A prototype lets engineers test ideas, collect evidence, and notice failure points.

📋 NGSS Standard:
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.

🎯 Learning Objective

Students will build a prototype, test it fairly, and record evidence about strengths and failure points.

💡 The Big Idea

Testing turns a plan into evidence. A prototype helps engineers see what really happens instead of guessing.

🔬 The Science

Science Snapshot

Prototype tests reveal how the design behaves under real challenge conditions.

What is happening?

A prototype is a first working version built so it can be tested. Engineers use prototypes to gather evidence about what works and what still needs improvement.

Why it works that way

During a drop test, the design may cushion, bounce, tip, crack, or fail in surprising ways. Those results are useful because they reveal how force moved through the system during impact.

Look for this in the lesson

Students should record what happened to the design and to the fragile object. The goal is to identify which part of the system protected well and which part needs redesign.

Ask while you read: What happened during the test that tells you where the design succeeded or failed?

Materials

🏠 Household Items to Gather

Printed lesson pages and worksheet
Pencil
Chosen building materials from previous lessons
Fragile-object stand-in for testing
A safe table-height drop space

📋 Printables

Student Worksheet page from this lesson

Let's Get Started

Step 1 — Build Version 1: Students use their chosen plan to build a first prototype.

Step 2 — Set Fair-Test Rules: Agree on the same drop height, object, and test surface for everyone.

Step 3 — Run the Drop Test: Students test the prototype and watch carefully for movement, cracks, or weak spots.

Step 4 — Record Evidence Right Away: Students note what stayed protected, what shifted, and what failed.

Step 5 — Name the Failure Point: Students explain which part of the design needs the most improvement.

Discussion Questions

Why do engineers build prototypes instead of finished products first?Look for answers like: Prototypes help them learn before making final decisions.

What makes this drop test fair?Look for answers like: The same important conditions stay the same for each test.

Why should students write observations right away?Look for answers like: Fresh notes are more accurate than trying to remember later.

What is a failure point?Look for answers like: The place where the design failed or struggled most.

Why is failure useful in engineering?Look for answers like: It shows what needs to improve.

Extensions

Extension: Run a second test from the same height and compare whether the result stayed consistent.

Extension: Film a slow-motion drop if your device allows and discuss what you notice.

Parent/Teacher Notes

Teaching note: Keep testing safe and simple. A toy or pretend fragile object can be used if an actual egg is not appropriate.

Teaching note: Reframe “it failed” as “we learned where it needs work.”

Student Worksheet

Name: ________________________ Date: ________________________

1️⃣ Describe Version 1

My prototype used ______________________________________________________.

2️⃣ Record the Fair Test

What stayed the same?	What happened in the test?

3️⃣ Identify the Failure Point

The weakest part of my design was ________________________________________.

The evidence I saw was _________________________________________________.

✂️ PARENT ANSWER KEY — Detach before giving worksheet to students

1️⃣ Describe Version 1 — Sample Use

Accept any description that matches the student prototype and design plan.

2️⃣ Record the Fair Test — Sample Use

Look for notes that mention a consistent drop height, same object, and specific observations such as shifting, bending, or protecting well.

3️⃣ Identify the Failure Point — Model Response

“The weakest part was the side support because it bent when the object landed, and the object slid toward that side.”

✅ What Success Looks Like

Student builds and tests a prototype.
Student records specific test observations.
Student identifies a plausible failure point using evidence.

🛠️ Troubleshooting / Teaching Notes

If a student only says “it worked” or “it failed,” ask what exactly happened to the object or structure.
If too many variables changed, help the student identify which test condition should stay consistent next time.