Solving Problems Like Engineers

The Phenomenon: A Lunch Box Problem

Your teacher gives the class a challenge: Design a better lunch container that keeps food cold, dry, and fresh for at least 4 hours. But wait — you can only use materials that fit inside your backpack, and you can only spend $5.00 on supplies. How do you start solving this problem?

• What exactly is the problem that needs to be solved here?
• What rules or limits does the class have to follow when designing a solution?
• How would you decide if one lunch container design is better than another?

What Engineers Know About Design Problems

Before engineers start building anything, they do something very important: they carefully define the problem they are trying to solve. This means they figure out exactly what the problem is, what a good solution needs to do, and what limits they have to work with. Let's explore the key ideas engineers use.

Let's Investigate: Defining a Design Problem

Your investigation: Let's practice defining a design problem the way a real engineer would. Imagine your school's playground has a problem: when it rains, the slides get slippery and dangerous, and the sandbox fills with water. The principal asks your class to come up with a solution.

Steps to define the problem:

• Identify the problem: Write one clear sentence about what needs to be fixed.
• List the criteria: What does the solution need to do? (Keep slides safe, keep water out of sandbox, still be fun to use)
• List the constraints: What are the limits? (Budget of $200, can't change the whole playground, must be safe for all ages)
• Check your work: Show your problem definition to a classmate. Can they understand the problem just from reading it?

What you would observe: Different teams might define the same problem in slightly different ways. Some teams might focus on keeping the slide dry, while others focus on covering the sandbox. Both are valid — but the criteria and constraints help everyone agree on what matters most.

What We Discovered: Criteria vs. Constraints

When engineers define a design problem, they separate their requirements into two groups: criteria and constraints. Let's look at how this works by going back to our lunch container challenge and another example.

Think of criteria as the "must-do" list — what the solution needs to accomplish. Think of constraints as the "can't-do" list — the limits that you have to work within. Both are important! A solution that meets all the criteria but ignores the constraints won't work in real life.

Notice how each problem has multiple criteria AND multiple constraints? That's normal! Real-world design problems are rarely simple. The job of the engineer is to find a solution that meets as many criteria as possible while staying within all the constraints. Sometimes, you can't meet every single criterion perfectly — and that's okay. Engineers prioritize and make trade-offs.

Patterns and Connections: Cause and Effect

Here's something interesting: the idea of identifying causes and effects shows up everywhere in science, not just in engineering! When engineers define a design problem, they are really asking: "What is causing the problem, and what effect does it have?" Understanding the cause helps them design a better solution.

Scientists look for patterns of cause and effect in everything they study. Let's see how this same idea connects across different areas of science:

Do you see the pattern? In every case, understanding what causes the problem is the first step to designing a solution. Engineers use cause-and-effect thinking to figure out what they need their design to do (criteria) and what they're working against (the cause of the problem).

Real-World Connections: Engineering All Around Us

Engineers define design problems with criteria and constraints every single day. Here are some real examples of how this works in the world around you:

Notice how every real engineering project starts with this same first step: clearly defining the problem, criteria, and constraints. Without this step, engineers might build something that looks great but doesn't actually solve the problem — or costs way too much money.

• Write the problem in one sentence.
• List 2–3 criteria (what must the solution do?).
• List 2–3 constraints (what are the limits?).

Share your problem definition with a classmate and see if they can think of solutions that fit your criteria and constraints!

Key Vocabulary Review

Key Vocabulary

• Design Problem — A need or want that can be solved by creating or improving an object, tool, process, or system. It's the starting point of the engineering design process.
• Criteria — The requirements that describe what a successful solution must do. Criteria tell you what success looks like. (Example: "The container must keep food cold for 4 hours.")
• Constraints — The limits or restrictions on a design solution. Constraints tell you what you have to work within. (Example: "The solution must cost less than $5.00.")
• Engineer — A person who uses science, math, and creativity to solve problems by designing and building things.
• Engineering Design Process — The series of steps engineers follow to define problems, develop solutions, and improve their designs. It includes: define the problem, brainstorm, plan and build, test, and improve.
• Trade-off — A choice where improving one thing might make another thing less ideal. Engineers often have to make trade-offs to meet constraints. (Example: A cheaper material might not keep food as cold.)
• Cause and Effect — The relationship between an event (cause) and what happens because of it (effect). Engineers study cause and effect to understand problems and design solutions.

Practice: Test Your Understanding

What's Next?