Compare how each design performs.

SECTION 1

Why Do We Compare Things?

People have always tried new ideas. Then they check which idea works best!

Long ago, people built bridges. They tried different shapes to see which one was strongest. That is comparing designs. That means looking at two or more things to see how they are different.

Long Ago

Building Shelters

People tried sticks, mud, and rocks. They picked what kept them dry!

Later

Making Boats

People tried logs and animal skins. They picked what floated best!

Even Later

Building Bridges

People tried flat boards and arches. They picked what held the most weight!

Today

Testing Everything!

Engineers test and compare designs every day. You can be an engineer too!

So how do we know which design is better? We test them and compare what happens. Let's learn how!

SECTION 2

Big Ideas About Comparing Designs

When we build something, we want it to work well. Here are the big ideas that help us compare.

Test Each Design

Try each design the same way. That means giving each one a fair test.

Watch What Happens

Use your eyes to see how each design works. This is called observing. That means looking carefully.

Talk About Differences

Tell a friend how the designs are different. Which one did a better job?

Pick the Best One

After you compare, you can choose which design solves the problem best!

✦ KEY TAKEAWAY

Comparing designs is like tasting two cookies. You try both and then you pick your favorite. Engineers do the same thing with their designs!

SECTION 3

See How Comparing Works

Let's look at a picture! Two friends each made a paper boat. They tested both boats in water. Let's compare!

Boat A is wide and flat. It floats well! Boat B is tall and thin. It sinks. When we compare, we can see Boat A works better for floating.

Did you see the difference? Boat A stayed on top of the water. Boat B sank. Now we know the wide shape works better!

SECTION 4

How Do We Compare Designs?

Comparing designs is like being a detective! You follow steps to find out which design is the winner.

Step-by-Step: How to Compare

Build two or more designs. Each one tries to solve the same problem.
Test them the same way. This is a fair test. That means you do the same thing to each one.
Watch carefully. Use your eyes. What do you see happening?
Talk about it. Tell a friend what you noticed. How were they different?
Pick the best one. Which design did a better job?

💡 Fair Test Tip!

A fair test means everything stays the same except the design. If you roll two toy cars, use the same ramp for both!

Remember, the most important thing is to keep the test fair. That way we really know which design is better.

SECTION 5

Different Ways to Compare Designs

There are many ways to compare! Let's look at some things we can check when we test our designs.

This picture shows five things we can check: How strong? How fast? How far? Does it float? Does it protect? Each one helps us compare designs.

You pick what to check based on the problem you are solving. If you want a boat, check if it floats. If you want a ramp, check how far a ball rolls!

SECTION 6

Let's Try It Together!

Two friends want to build a ramp for a toy car. They want the car to roll far. Let's compare their ramps!

Comparing Two Ramps

Step 1 — Build Two RampsSam uses a big book. Mia uses a small book. Both lean the book on a box to make a ramp.

Two ramps are ready to test!

Step 2 — Give a Fair TestThey use the same toy car. They let it go from the top. They do NOT push it. This is a fair test.

Same car, same start, no pushing.

Step 3 — Watch CarefullyOn Sam's big-book ramp, the car rolls far across the floor. On Mia's small-book ramp, the car rolls a little bit.

Sam's car went farther!

Step 4 — Compare and TalkSam and Mia talk about what they saw. Sam's ramp was taller. The car went faster and farther on the taller ramp.

The taller ramp made the car go farther!

Step 5 — Pick the Best DesignBoth friends agree. If you want the car to go far, use a taller ramp. They compared and found the best design!

Sam's taller ramp wins!

SECTION 7

What Makes Comparing Easy or Hard?

Comparing designs is really helpful. But sometimes it can be tricky! Let's look at what helps and what is hard.

Helpful things and tricky things when comparing designs

What Helps Us Compare	What Can Be Tricky
Using a fair test every time	Forgetting to keep the test the same
Watching very carefully	Going too fast and missing something
Talking about what you see	Not knowing the right words yet
Trying the test more than once	Only trying once and guessing

✦ KEY TAKEAWAY

Comparing designs is like a race at recess. You need to start at the same spot and run the same distance. If one person starts closer, the race is not fair! Keep your test fair and you will find the best design.

SECTION 8

What Do Engineers Do After Comparing?

Great engineers do not stop after one test! They keep making things better. Let's see what happens next.

Kindergarten comparing vs. what comes next

What You Do Now	What Engineers Do Later
Compare two designs	Compare many designs at once
Use your eyes to watch	Use tools like rulers and timers
Talk about what you see	Write down data in charts
Pick the best design	Make the best design even better

You are already thinking like an engineer! As you grow, you will learn to use tools and numbers to compare even better.

SECTION 9

Your Turn to Think!

Two friends made umbrellas for a stuffed animal. They want to keep the stuffed animal dry in the rain. Let's think about their designs!

PROBLEM 1 — CONCEPTUAL

Why should the friends test both umbrellas? A) Because testing is silly. B) To see which one keeps the stuffed animal dry. C) Because they are bored.

PROBLEM 2 — BASIC OBSERVATION

Lily's umbrella is made of paper. Max's umbrella is made of a plastic bag. After pouring water, Lily's umbrella gets soggy and the stuffed animal is wet. Max's umbrella stays strong and the stuffed animal is dry. Which umbrella worked better? A) Lily's paper umbrella. B) Max's plastic bag umbrella. C) They both worked the same.

PROBLEM 3 — INTERMEDIATE

What makes this a fair test? A) Using different stuffed animals for each umbrella. B) Pouring the same amount of water on each umbrella. C) Only testing one umbrella.

PROBLEM 4 — APPLIED

Max wants to make his umbrella even better. What should he do next? A) Throw it away and give up. B) Make it bigger so it covers more of the stuffed animal and test it again. C) Not test it because it already works.

PROBLEM 5 — CRITICAL THINKING

Think and share with a friend: What if you had to make a tiny house for an ant to keep it dry? What would you use? How would you test two different designs? Tell your friend your idea!

SUMMARY

What We Learned

Today we learned how to compare designs! We build two or more things and give them a fair test. That means we test them the same way. Then we observe what happens. We look carefully and talk about what we see.

After testing, we pick the best design. The best design is the one that solves the problem the best. You are an engineer! Keep testing, comparing, and making things better!