Design Success Criteria — Describe criteria for success. |...

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Why Do We Need Success Criteria?

Have you ever built something and then wondered, "Did it turn out right?" People have been asking that question for a very long time! Engineers are people who design and build things to solve problems. Long ago, they learned that they needed a way to check if their work was good enough. That is why they started using success criteria — clear rules that describe what a successful design looks like.

3000 BCE

Ancient Builders Set Goals

The ancient Egyptians built pyramids. They decided ahead of time how tall, how strong, and how smooth the pyramids needed to be. Those were early success criteria!

1400s

Leonardo da Vinci's Designs

Leonardo da Vinci drew plans for flying machines and bridges. He wrote down what each invention needed to do, like carry a certain weight or fly a certain distance.

1900s

The Wright Brothers' Airplane

The Wright Brothers wanted a plane that could stay in the air for at least 12 seconds and carry a person. Those clear goals helped them test and improve their design.

Today

Engineers Everywhere Use Success Criteria

Today, engineers who build bridges, toys, apps, and rockets all write down success criteria before they start. It keeps them focused and helps them know when they are done.

So here is the big question: How do you decide if a design is good enough before you even start building? That is what this lesson is all about!

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What Are Success Criteria?

Success criteria are the rules or goals you set before you start building something. They tell you exactly what your design needs to do to count as a success. Think of them like a checklist that you can use to test your design when it is finished.

Measurable

Good success criteria use numbers or clear descriptions. Instead of saying "it should be strong," say "it should hold 10 books without breaking."

Connected to the Problem

Success criteria should match the problem you are trying to solve. If the problem is keeping rain off your head, your criteria should be about staying dry!

Testable

You should be able to check each criterion. Can you observe it, measure it, or try it out? If yes, it is a good criterion.

Agreed On by the Team

Everyone on the team should agree on what success looks like before building starts. This way, nobody is surprised at the end.

✦ KEY TAKEAWAY

Think of success criteria like a recipe for cookies. The recipe tells you what the cookies should taste like, how big they should be, and how long to bake them. Without the recipe, you are just guessing! Success criteria are the recipe for a good design.

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Seeing Success Criteria in Action

Let's look at how success criteria fit into the engineering design process. The diagram below shows where success criteria appear. Notice that they come early in the process, right after you understand the problem.

This flowchart shows the engineering design process. Notice how Step 2 — Set Success Criteria happens right after defining the problem. Later, in Step 5, you test your design against those criteria.

As you can see, success criteria connect Step 2 to Step 5. You set the goals early, then check your design against those goals later. If your design does not meet the criteria, you go back and improve it. This loop keeps going until your design passes all the tests!

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How to Write Success Criteria

Writing good success criteria takes practice. Here is a simple method you can use every time. Think of these three questions: What should it do?, How well should it do it?, and How will I test it?

The Three-Question Method

What should it do? — Describe the main job of your design. For example, "It should keep a marble rolling for a long time."
How well should it do it? — Add a number or a clear description. For example, "The marble should roll for at least 10 seconds."
How will I test it? — Explain how you will check. For example, "I will use a timer to measure how long the marble rolls."

💡 Tip: Vague vs. Specific

A vague criterion says: "It should be strong." A specific criterion says: "It should hold 5 heavy books without bending." Specific is always better because you can actually test it!

Examples of vague vs. specific success criteria

Vague Criterion ❌	Specific Criterion ✅
It should be tall.	It should be at least 30 centimeters tall.
It should look nice.	It should use at least 3 different colors.
It should work fast.	It should finish the task in under 20 seconds.
It should not break.	It should survive being dropped from 1 meter high.

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Different Types of Success Criteria

Not all success criteria are the same. Engineers sort them into different types so they can be sure they have not forgotten anything important. Let's look at the main types you might use in your own designs.

Five common types of success criteria: Function (what it does), Size & Shape (how big it is), Materials (what it is made of), Safety (is it safe), and Time (how fast it works).

When you start a design project, try to write at least one success criterion from each type. That way, you cover all the important parts of your design. You might not need every type every time, but thinking through all five helps you make a complete plan.

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Worked Example: Building a Paper Bridge

Let's walk through a real design challenge step by step. Imagine your teacher says: "Build a bridge out of paper that can hold pennies." Here is how you would write success criteria.

Paper Bridge Design Challenge

Step 1 — Understand the ProblemThe problem is that you need a bridge that connects two stacks of books and holds pennies on top. Ask yourself: What does this bridge need to do?

Problem: Build a paper bridge that holds pennies across a gap.

Step 2 — Write Function CriteriaAsk: "What should the bridge do?" It should hold pennies without falling down. Let's make it specific.

Criterion 1: The bridge must hold at least 20 pennies without collapsing.

Step 3 — Write Size CriteriaAsk: "How big does it need to be?" The gap between the book stacks is 20 centimeters.

Criterion 2: The bridge must span a gap of at least 20 centimeters.

Step 4 — Write Materials CriteriaAsk: "What can I use?" The teacher said paper only, plus tape to hold pieces together.

Criterion 3: The bridge must be made using only 5 sheets of paper and tape.

Step 5 — Plan How to TestNow decide how you will test each criterion. You will place the bridge across the gap, then add pennies one by one and count them. You will use a ruler to check the gap.

Test Plan: Place bridge across books, add pennies one at a time, measure gap with ruler.

🔍 Notice Something?

Every criterion uses a number (20 pennies, 20 centimeters, 5 sheets). Numbers make it easy to test. You either meet the number or you don't. There is no arguing about it!

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Good Criteria vs. Bad Criteria

Not all success criteria are created equal. Some criteria help a lot, and some are not very useful. Let's compare good and bad criteria side by side so you can learn to write the best ones.

Comparing good and bad success criteria

Feature	Good Criteria ✅	Bad Criteria ❌
Specific	Uses numbers and clear words	Uses vague words like "good" or "nice"
Testable	You can observe or measure it	You cannot really check it
Connected	Matches the problem you are solving	Talks about something unrelated
Fair	Any team can check the same way	Different people would disagree

✦ KEY TAKEAWAY

Think of success criteria like the rules of a game. In soccer, everyone agrees the ball must go into the goal to score a point. That is specific and testable. If the rule were just "play well," nobody would agree on who won! Good success criteria are like clear game rules — they make it fair and easy to judge.

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How Success Criteria Grow with You

Right now, you are learning the basics of writing success criteria. As you get older, this skill will grow with you! Engineers, scientists, and even game designers use success criteria every day. The ideas get bigger, but the main skill stays the same.

Your success criteria skills will grow over time

What You Learn Now	What Comes Next
Write criteria with numbers	Use data tables and graphs to check criteria
Test a simple design once	Run multiple tests and compare results
Decide pass or fail	Rank designs from best to worst using a scoring system
Work on one design challenge	Balance many criteria at the same time (cost, weight, speed)

In later grades, you will learn about constraints (limits on your design, like a budget) and trade-offs (giving up one good thing to get another). For now, just focus on writing clear, testable, specific success criteria. You are building a skill that real engineers use every day!

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Practice Problems

Now it is your turn! Try these five problems. They start easy and get harder as you go. Think carefully about what makes a success criterion good.

PROBLEM 1 — CONCEPTUAL

What is a success criterion? Explain it in your own words using one or two sentences.

PROBLEM 2 — BASIC

Your class is designing a container to keep an egg safe when dropped from 1 meter. Which of these is a better success criterion and why? (A) "The egg should not break." (B) "The egg should have no cracks after being dropped from 1 meter onto a hard floor."

PROBLEM 3 — INTERMEDIATE

You are designing a boat made from aluminum foil. The boat should float and hold as many marbles as possible. Write two specific, testable success criteria for this design challenge.

PROBLEM 4 — APPLIED

Your school needs a new recycling bin for the lunchroom. It must be easy for students to use and hold enough trash for one lunch period. Write three success criteria using at least two different types (function, size, materials, safety, or time).

PROBLEM 5 — CRITICAL THINKING

Two teams built different paper airplanes. Team A's plane flew 8 meters. Team B's plane flew 6 meters but landed closest to a target. Both teams said they won. What went wrong? How could success criteria have prevented this argument?

SUMMARY

Lesson Summary

Success criteria are clear rules you write before you start building to describe what a successful design looks like. Good criteria are specific (they use numbers or clear descriptions), testable (you can check them by measuring or observing), and connected to the problem you are trying to solve.

There are five common types of criteria: function (what it does), size and shape (how big it is), materials (what it is made of), safety (is it safe to use), and time (how fast it works). When your whole team agrees on the criteria, everyone works toward the same goal. Remember the three-question method: What should it do? How well should it do it? How will I test it?