--- title: "Simple Design Problems" description: "Define a simple design problem reflecting a need or want that includes specified criteria for success and constraints on materials, time, or cost" canonical: https://lightmysky.com/learn/science/simple-design-problems-mt_Z5-fSCOBep source: https://lightmysky.com/learn/science/simple-design-problems-mt_Z5-fSCOBep.md retrieved: 2026-10-19 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Simple Design Problems Define a simple design problem reflecting a need or want that includes specified criteria for success and constraints on materials, time, or cost Subject: Science · Area: Scientific Inquiry · Ages 8 to 11 Page: https://lightmysky.com/learn/science/simple-design-problems-mt_Z5-fSCOBep ## Ready when they can - Define a design problem by describing the need or want it addresses - Specify at least two criteria for a successful solution, such as holding a stated load and staying upright for a stated time - Identify constraints such as available materials, time limits, or cost ## Lesson: Naming a design problem You have compared designs using goals and test results. Before starting a new design, state the need or want it should meet. A complete plan names that need, gives at least two success rules called criteria, and lists limits called constraints. **Example.** Mia needs a model bridge to carry toy cargo across a gap. Her criteria are to hold 6 blocks without bending and stay upright for 20 seconds. Her constraints are 12 straws, one roll of tape and 10 minutes. This is a classroom model, not a bridge for people. Criteria say what a design must do. Make them clear enough to check. 'Stand without help' is testable without a number. 'Looks nice' needs a clearer judging rule. To compare number targets, count up from the smaller one. From 1 to 6 is five steps, so a target of 6 is 5 more. *(drawing: These six blocks are the test load. The picture does not show whether the model bridge can hold them.)* Constraints limit what you can use or do, such as materials, time or cost. Here, rules about the design's job are criteria, and building limits are constraints. A $4 cost cap is a constraint here, even though you can check it with a number. A number alone does not tell you the kind of rule. Turn vague rules into checks. Instead of 'strong enough', say what load it must hold. Test every criterion. A holder that keeps 2 pens inside but falls over does not meet a rule to stand alone. Check the constraints too. If a plan breaks an agreed limit, revise it and check again. You can ask whether the limit may change, but do not change an agreed rule by yourself. A plan using 9 cards does not fit a limit of 7 cards. **Recap.** A design problem names the need, gives at least two criteria for success, and lists the constraints on materials, time, or cost. ## Practice 12 questions on this page, each with its working shown. ## Needs first - [Comparing Design Solutions](https://lightmysky.com/learn/science/comparing-design-solutions-mt_nNYo5A-7Bl) ## Opens up - [Comparing Possible Solutions](https://lightmysky.com/learn/science/comparing-possible-solutions-mt_HveO1bOXpJ)