Improving Based on Tests — Use test results to suggest improvements. - 3rd Grade Science

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Why Do Engineers Test and Improve?

Have you ever built something and thought, "Hmm, I can make this better"? That is exactly what engineers do every single day! Engineers are people who design and build things to solve problems. But here is a secret: their first try almost never works perfectly. They have to test their designs and then make changes to improve them.

Throughout history, inventors and engineers have used testing and improving to create amazing things. Let's look at some cool examples!

1903 • The Wright Brothers' Airplane

The Wright Brothers tested over 200 different wing shapes before they built a plane that could really fly. Each test told them what to change!

1947 • Silly Putty Was an Accident!

An engineer was trying to make rubber. His test showed the material was too bouncy. But that "failure" became a favorite toy!

1969 • Apollo Moon Landing

NASA tested rockets hundreds of times. Each test showed engineers what needed fixing before astronauts could safely travel to the moon.

2012 • Mars Rover Curiosity

Engineers tested the Mars rover's wheels, cameras, and parachute many times. Each test result helped them improve the design for the rocky surface of Mars.

All of these inventors asked the same big question: "What did my test results tell me, and how can I use that information to make my design better?" That is exactly what you will learn in this lesson!

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Core Ideas About Testing and Improving

When engineers want to solve a problem, they follow a process. First they design a solution, then they build it, then they test it. Testing means trying out the design to see how well it works. After testing, they look at the results (what happened during the test) to figure out what to change. Here are the big ideas you need to know.

Test Results Are Clues

Test results are like clues in a mystery. They tell you what is working well and what is not. Pay close attention to what happens during your test!

Failure Is Helpful

When something does not work, that is not bad news. It is useful information! A failure tells you exactly what part of your design needs to change.

Change One Thing at a Time

When you improve your design, try changing just one thing. That way, you can tell if your change actually made things better or worse.

Compare to the Goal

Always compare your test results to the goal or problem you are trying to solve. Ask: "Did my design do what it was supposed to do?"

Test Again After Improving

After you make a change, test your design again! This is called the design cycle. Engineers go around this cycle many times.

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KEY TAKEAWAY

Think of improving a design like learning to ride a bike. The first time you try, you might wobble or fall. But each time you fall, you learn something — maybe you need to go a little faster, or lean a different way. You use what you learned to do better next time. That is exactly what engineers do with test results!

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The Design Cycle — A Visual Guide

Engineers follow a cycle when they design things. It goes around and around because they keep improving! The diagram below shows the Engineering Design Cycle. Notice how "Test" leads to "Improve" — that is the focus of our lesson today.

The Engineering Design Cycle has five steps. Step 5, Improve, is highlighted because it is the focus of this lesson. After you test, you look at the results and decide what to change. Then the cycle starts again!

Look at the arrows in the diagram. After you test your design, the arrow leads to improve. Then the arrow goes all the way back to the beginning. This means you can go through the cycle as many times as you need to make your design great!

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How Do You Use Test Results to Improve?

So your test is done. Now what? You need to look carefully at your test results and figure out what they are telling you. Here is a step-by-step way to do that.

Step-by-Step: From Test Results to Improvements

Look at what happened. Write down or draw what you saw during the test. Did your design do what you wanted?
Find the problem. If something went wrong, figure out which part caused the problem. Was it too heavy? Too short? Not strong enough?
Think of a change. Come up with one idea for how to fix the problem. Remember, change only one thing at a time!
Make the change. Rebuild or adjust your design with the improvement you thought of.
Test again! Run your test one more time to see if the change helped. If it did not, go back and try a different change.

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Important Tip!

When you write down your test results, use numbers if you can! For example, instead of saying "the ball did not go very far," say "the ball rolled 2 feet." Numbers help you compare your results before and after you make a change.

Let's say you built a ramp for a toy car, and your goal was for the car to roll at least 5 feet. Your test showed the car only rolled 3 feet. Your test result (3 feet) tells you the ramp needs a change. Maybe you make the ramp taller so the car goes faster. Then you test again and measure how far the car goes this time.

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What Kinds of Improvements Can You Make?

When your test results show a problem, there are different kinds of changes you can try. The diagram below shows three main types of improvements engineers think about.

Three types of improvements you can make: change the materials, change the shape or size, or change the method (how you put things together). Your test results will help you decide which type of change to try!

Test Result (Problem)	Type of Change	Example Improvement
The tower fell over	Change the shape	Make the base wider
The boat sank	Change the materials	Use tin foil instead of paper
The pieces kept falling apart	Change the method	Use tape instead of just balancing
The car only rolled 2 feet	Change the size	Make the ramp taller

Common test problems and how to choose the right type of improvement

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Worked Example: The Paper Bridge Challenge

Let's walk through a real example together! Imagine your class has a challenge: build a bridge out of paper that can hold at least 10 pennies. Let's see how one student uses test results to improve their design.

The Paper Bridge Challenge

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Step 1 — Build and Test the First Design

Maria lays a flat sheet of paper across two stacks of books. She places pennies on top one at a time. The paper bends and the pennies slide off after just 3 pennies.

Test Result: The bridge held only 3 pennies. The goal is 10.
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Step 2 — Look at the Results and Find the Problem

Maria looks at her test results. The paper sagged in the middle. The problem is that a flat sheet of paper is not strong enough. It bends too easily.

Problem Found: The flat paper bends in the middle.
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Step 3 — Think of an Improvement

Maria remembers that folded paper is stronger than flat paper. She decides to fold her paper into an accordion shape (back and forth like a fan). This is changing the shape of her design.

Improvement: Fold the paper into an accordion shape.
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Step 4 — Rebuild and Test Again

Maria folds the paper and places it across the books again. She adds pennies one by one. This time, the bridge holds 8 pennies before it starts to bend!

New Test Result: 8 pennies. Better, but still not 10!
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Step 5 — Improve Again!

Maria is close! She notices the folds are big and floppy. She decides to make the folds smaller and tighter. She rebuilds and tests again. This time the bridge holds 12 pennies! She passed the goal!

Final Result: 12 pennies! Goal of 10 pennies reached! ✓

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Did You Notice?

Maria went through the design cycle three times (3 pennies → 8 pennies → 12 pennies). Each time, her test results told her what to fix. She changed one thing at a time and tested again. That is exactly how real engineers work!

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Good Improvements vs. Not-So-Good Improvements

Not all improvements are created equal! Some changes are smart because they are based on what you learned from your test. Other changes are just random guesses. Let's compare the two.

Good Improvement ✅	Not-So-Good Improvement ❌
Based on what the test results showed	A random guess with no connection to the test
Changes one thing at a time so you can track what helps	Changes many things at once so you cannot tell what helped
Focuses on the part that failed	Changes a part that was already working fine
Uses numbers from the test to set a new goal	Does not measure or compare results
Tests again after making the change	Assumes the change worked without testing

Comparing smart, evidence-based improvements with random changes

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KEY TAKEAWAY

Imagine you are playing a video game and you keep losing at the same level. A good improvement is like watching what beats you each time and changing your strategy for that one problem. A not-so-good improvement is like pressing random buttons and hoping for the best. Use your test results like a game guide — they show you exactly what to fix!

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How Real Engineers Improve Designs

You might think that improving designs is just something you do in school. But real engineers in the real world do this every day! Let's see how the testing-and-improving process you are learning connects to what grown-up engineers do.

What You Do in Class	What Real Engineers Do
Build a paper bridge and test how many pennies it holds	Build a model bridge and test how much weight it can carry safely
Write down your test results in a notebook	Record test data on computers with special software
Change the shape or material and test again	Create a new version (called a prototype) and run more tests
Go through the design cycle 2–3 times	Go through the design cycle hundreds of times over months or years
Share your improvement ideas with your group	Share test results with a whole team of engineers and scientists

Your classroom engineering process is the same process real engineers follow

A company that makes sneakers might test 50 different designs before picking the best one. Car companies crash-test cars and then improve the safety features. Video game designers test their games with real players and fix anything that is confusing or buggy. The idea is always the same: test, learn, improve, repeat.

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Looking Ahead

As you get older, you will learn more about how engineers use math and science to predict what will happen before they even build anything. But the big idea stays the same — test your ideas and use the results to make them better!

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Practice Problems

Now it is your turn! Read each problem and think about how you would use test results to suggest improvements. Try to answer each one before looking at the answer.

Question 1: CONCEPTUAL

Why is it important to look at your test results before you change your design? Why not just guess what to change?

Show answer

Test results give you real information about what went wrong. If you just guess, you might change something that was already working and make the problem worse. By looking at your results, you can find the exact part that needs fixing. This saves time and helps you make smarter choices. Engineers always use evidence (real information) to decide what to improve.

Question 2: BASIC CALCULATION

Jake built a tower out of blocks. His goal was 12 inches tall. He tested it and it was 8 inches tall before it fell over. How many more inches does he need? If he makes the base wider and the new tower reaches 11 inches, is he closer to his goal?

Show answer

Jake needs 12 − 8 = 4 more inches to reach his goal. After making the base wider, his new tower is 11 inches tall. He is now only 1 inch away from his goal instead of 4 inches away. Yes, he is much closer! His improvement (a wider base) helped the tower stay up taller. He should test one more change to try to reach 12 inches.

Question 3: INTERMEDIATE

Mia built a boat out of tin foil to hold marbles. In Test 1, it held 5 marbles and then sank. She made the sides taller and in Test 2, it held 8 marbles. Then she also made the boat wider, and in Test 3 it held 14 marbles. Which change do you think helped more — taller sides or a wider bottom? Explain your thinking.

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From Test 1 to Test 2, Mia made the sides taller and went from 5 to 8 marbles. That is an improvement of 3 marbles. From Test 2 to Test 3, she made the boat wider and went from 8 to 14 marbles. That is an improvement of 6 marbles. The wider bottom helped more because it added 6 extra marbles compared to only 3 for the taller sides. A wider bottom gives the boat more space to spread out the weight of the marbles.

Question 4: APPLIED

Your class built a catapult to launch a cotton ball. The goal is to land the cotton ball inside a bucket 6 feet away. In the first test, the cotton ball only flew 3 feet. In the second test, after making the arm longer, it flew 9 feet and went over the bucket. Suggest an improvement for the third test and explain why.

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The first test showed the catapult was not powerful enough (3 feet was too short). Making the arm longer helped, but now it launches too far (9 feet is past the bucket). For the third test, you could make the arm a little shorter than the second design — maybe somewhere between the first and second lengths. Another idea is to keep the long arm but use less force when you launch. The key is that the cotton ball needs to go less far than 9 feet but more than 3 feet. You are using both test results as clues!

Question 5: CRITICAL THINKING

Sam tested his car ramp design three times. In Test 1 the car rolled 4 feet. In Test 2 he changed the ramp material AND the ramp height, and the car rolled 7 feet. Sam says the new material made the car go farther. Is Sam right to say that? What would you tell Sam about how to test properly?

Show answer

Sam cannot be sure it was the new material that helped because he changed two things at the same time — the material AND the height. The extra distance could have come from the taller ramp, or the new material, or both together. You would tell Sam that he should change only one thing at a time. He should test with just the new material first, then test with just the new height. That way he can figure out which change actually made the car roll farther. This is a very important rule in engineering and science: change one variable at a time so your results are clear.

SUMMARY

Lesson Summary

Summary

In this lesson, you learned that engineers test their designs and use the test results to figure out what to change. The Engineering Design Cycle goes around and around: Ask, Design, Build, Test, and Improve. When you improve, you can change the materials, change the shape or size, or change the method you use to build.

The most important rules to remember: always change one thing at a time so you know what helped, use numbers to measure your results so you can compare, and always test again after making a change. Failures are not bad — they are useful clues that help you make your design better. Real engineers do this same process every day, and now you can too!