Establishing Design Criteria

Introduction: turning a need into a clear direction

In IB Design Technology SL, a successful design project begins with a real problem and a clear understanding of who the solution is for. Before any sketches become a model, and before any prototype is tested, students must define the design criteria. Design criteria are the specific, measurable statements that describe what a good solution should achieve. They are the bridge between a client’s needs and the designer’s decisions. 🎯

This step matters because a project without criteria can become vague, unfocused, and hard to evaluate. For example, if a school wants a better lunch tray, “make it better” is too unclear. A good design brief would turn that idea into criteria such as $\text{weight} < 500\text{ g}$, easy to clean, safe to carry, and suitable for $30$ students in a cafeteria queue. These criteria guide development, testing, and final evaluation.

By the end of this lesson, students should be able to explain what design criteria are, how they are developed from research and stakeholder needs, and how they support the wider design project and practical programme. You will also see how criteria are used to judge whether a final product really solves the original problem.

What design criteria are and why they matter

Design criteria are the list of requirements that a design must meet. They are not random wishes. They should be based on evidence from the client, target audience, and end-user, as well as research into materials, ergonomics, safety, and function. In IB Design Technology SL, criteria are usually written as clear statements that can be tested later.

A strong criterion has three important qualities:

It is clear, so everyone understands it.
It is measurable or testable, so it can be checked later.
It is relevant to the problem, client, and user.

For example, suppose the client is a local sports club needing a portable equipment storage box. Weak criteria might be: “It should look good” or “It should be easy to use.” These ideas are useful, but they are too vague on their own. Stronger criteria would be: “The box should weigh less than $8\text{ kg}$ when empty,” “It should hold at least $6$ balls and $4$ cones,” and “It should be lifted safely by one adult.” These statements can be tested during development and evaluation.

Design criteria are also important because they keep the project focused. A design project may involve many possible ideas, but criteria help students choose the best one and avoid wasting time on features that do not address the main need. ✅

Building criteria from the client, target audience, and end-user

A key part of this topic is understanding the difference between the client, the target audience, and the end-user. These terms are related, but they are not always the same.

The client is the person or organisation that commissions the design.
The target audience is the group the product is aimed at.
The end-user is the person who actually uses the product.

In some projects, all three may be the same. In others, they may differ. For example, a company may commission a water bottle for teenagers, meaning the company is the client, teenagers are the target audience, and the end-user is also the teenager. In another case, a hospital may ask for a wheeled storage cart used by nurses, so the client is the hospital, but the end-users are the nurses.

To establish good criteria, students should first collect information from these stakeholders. This can include interviews, questionnaires, observation, and existing product research. The designer then turns that information into design requirements. For example, if users say a bottle should fit in a backpack and be easy to open with one hand, the criteria could include: “The bottle must have a diameter smaller than $8\text{ cm}$” and “The lid must be opened using one hand in under $3\text{ s}$.”

This process shows how design criteria are not invented in isolation. They are grounded in evidence. If the evidence changes, the criteria may need to be refined. That is normal in design thinking. 🧠

Turning research into measurable statements

The strongest criteria are specific. They often use numbers, limits, or clear performance descriptions. This makes them useful for testing later in the project.

A good method is to ask: “How will we know whether this design is successful?” If the answer can be measured, the criterion is probably strong.

Here are examples of turning vague ideas into measurable criteria:

Vague: “It should be light.”
Better: “The final product should weigh less than $1.5\text{ kg}$.”
Vague: “It should be comfortable.”
Better: “The handle should fit an average hand grip with a width of $3\text{ cm}$ to $4\text{ cm}$.”
Vague: “It should last a long time.”
Better: “The product should withstand $500$ opening and closing cycles without failure.”
Vague: “It should be safe.”
Better: “No sharp edge should have a radius smaller than $2\text{ mm}$.”

Not every criterion must be numerical, but every criterion should still be testable. For example, “The product should be easy to clean” can be tested by checking whether the main surfaces can be wiped with a cloth and whether food traps are avoided. In this way, qualitative ideas can still become practical evaluation points.

students should also avoid creating too many criteria. A long list can become confusing. Instead, choose the most important requirements, usually grouped into function, user, aesthetics, size, materials, safety, sustainability, and cost. This helps the project stay focused and realistic.

Using design criteria during modelling, testing, and development

Design criteria are not only written at the start of a project. They are used throughout the practical programme. As the design develops, criteria help the designer compare ideas, choose materials, and improve prototypes.

For example, imagine a student designing a desk organiser for a classroom. One criterion might be that it must hold $10$ pens, $5$ markers, and $1$ pair of scissors. During modelling, the student can build a quick card model to check proportions. During testing, the student can place the actual items into the prototype and count whether the storage requirement is met. If the organiser fails, the design is refined.

This is important because design is iterative. Iterative means repeating a cycle of making, testing, evaluating, and improving. Criteria act like checkpoints. They tell students whether a prototype is moving in the right direction or whether changes are needed.

A strong development record often includes:

the original criteria,
sketches or digital ideas,
prototype results,
evidence from tests,
changes made after testing,
and a final judgement about whether each criterion was met.

This also connects to documentation and communication. Good records show the reasoning behind each decision, which is a major part of IB Design Technology SL. Clear communication helps others understand not only what was made, but why it was made that way.

Writing criteria that are fair and realistic

When establishing design criteria, students must make sure the criteria are realistic. A criterion should challenge the design, but it should still be possible within the available time, tools, materials, and skill level.

For example, if a student is making a classroom lamp, a criterion like “The lamp must be powered by renewable energy only” may be possible, but only if the project has access to suitable components and enough time for safe development. If a criterion is too extreme or too expensive, it may prevent the project from being completed well.

A balanced set of criteria often includes:

functional requirements, such as what the product must do,
user requirements, such as what the end-user needs,
technical requirements, such as size or material limits,
and design requirements, such as appearance or style.

For example, a school timetable holder might have these criteria:

It must hold $1$ timetable card in an upright position.
It must fit on a desk with a footprint smaller than $20\text{ cm} \times 15\text{ cm}$.
It must be made from materials that are safe for classroom use.
It should be visually appealing to students aged $11$ to $16$.

These criteria are balanced, specific, and linked to the user. That makes them useful for both design and evaluation.

Conclusion

Establishing design criteria is one of the most important early steps in the design project and practical programme. It changes a broad problem into a clear set of requirements that can guide development, testing, and final evaluation. For students, the key idea is that good criteria are based on evidence, focused on the client and end-user, and written so they can be checked later. When criteria are clear and realistic, they improve decision-making and make the whole project stronger. In IB Design Technology SL, this is what turns creative ideas into purposeful, testable design work. ✏️

Study Notes

Design criteria are specific statements that describe what a successful solution must achieve.
Good criteria are clear, measurable, relevant, and testable.
The client commissions the design, the target audience is the intended group, and the end-user is the actual user.
Evidence for criteria can come from interviews, questionnaires, observations, and product research.
Vague ideas should be rewritten as measurable requirements, such as $\text{weight} < 1.5\text{ kg}$ or $500$ test cycles.
Criteria guide modelling, testing, development, and final evaluation.
Design work is iterative, so criteria are used repeatedly to improve prototypes.
Strong criteria should be realistic, balanced, and linked to the design brief.
Good documentation shows how each criterion was used to make decisions.
Establishing design criteria helps connect the original problem to a practical, testable solution.