Prototype for PMs

Kevin Lee
By
Kevin Lee
Kevin Lee
Kevin Lee
Kevin is a Co-Founder of ProductHQ. He has worked as a VC at Pear Ventures where he invested in and partnered with…
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A prototype is a representation of a product idea that lets me learn before I commit to building the real thing. It can be a sketch, a clickable flow, a role-play, a coded slice, or something else that makes a question observable. I do not judge a prototype by how polished it looks. I judge it by whether it helps me learn something important with less cost and risk than implementation.

I use prototypes when the team has an idea, an assumption, or a decision that is still open. The goal is not to create a miniature version of the finished product. The goal is to make the riskiest part of the idea concrete enough for customers, partners, or teammates to react to. That distinction keeps a prototype from quietly becoming a promise.

Start with a learning question

I begin by writing down the decision the prototype should inform. I might want to learn whether people understand a new workflow, whether an administrator can configure it, whether a proposed service fits an existing habit, or whether two concepts solve the same problem in different ways. “Get feedback on the idea” is too broad to guide the work.

My prototype brief usually includes:

  1. The decision that is still open.
  2. The assumption with the most important uncertainty.
  3. The audience or situation I need to represent.
  4. The behavior or explanation that would count as useful evidence.
  5. What the prototype deliberately leaves out.
  6. The next decision I will make after the learning activity.

This brief protects me from polishing the wrong detail. If I am testing whether the sequence of steps makes sense, visual polish may be a distraction. If I am exploring trust in a sensitive workflow, the language and permission model may deserve more attention than the layout.

Match fidelity to the question

I choose fidelity deliberately. A low-fidelity sketch is often enough to compare concepts or discuss the order of a workflow. A storyboard can help me explore a service that includes people, handoffs, or offline moments. A clickable prototype can make navigation and task language easier to discuss. A coded slice may be appropriate when performance, device behavior, or a technical constraint is itself part of the question.

Higher fidelity is not automatically better. It can cause people to comment on colors, spacing, or small controls when I need to know whether the underlying concept is useful. It can also make internal stakeholders feel that a decision has already been made. I label the prototype as a learning artifact and explain what is simulated, missing, or not yet supported.

I also avoid false precision. A prototype should not imply that a legal, operational, or technical detail has been solved when it has only been drawn. If a flow shows a notification, I explain whether the timing is real. If it shows a recommendation, I explain whether the content is representative or manually selected. Honest boundaries produce better feedback.

Prototype the riskiest part first

I look for assumptions that could invalidate the idea. They may involve customer motivation, comprehension, access, trust, operational feasibility, or technical behavior. I do not try to model every screen before testing the assumption that matters most.

For example, if the idea depends on a team agreeing on a shared approval step, I prototype that decision and the surrounding roles before designing a complete settings area. If it depends on a person recognizing a new status, I test the label and explanation in context. If the risk is a back-office handoff, I represent the handoff instead of spending time on a customer-facing animation.

I keep alternate concepts visible when the decision is genuinely open. Comparing two or three approaches can reveal the tradeoff more clearly than asking people to improve one option. I explain that the concepts are not a vote on a finished design. I am trying to understand which assumptions hold and which need more work.

Run a focused learning session

I give participants enough context to attempt the task without coaching them toward my preferred answer. I describe the situation, ask what they expect to do, and observe where their interpretation differs from mine. I ask follow-up questions about their reasoning rather than asking whether they “like” the prototype.

I distinguish between reactions to the artifact and evidence about the product idea. Someone may dislike a label but still understand the task. Someone may say a flow looks easy while missing a required step. I record what the person tried, what they expected, what blocked them, and what they suggested. I keep my own interpretation separate from the observation.

I also state the prototype’s limits before the session. A participant should not believe that entering real information will create a real account or trigger a real transaction. If the subject is sensitive, I use fictional data and a consent process appropriate to the situation. A fast learning cycle is not a reason to skip respect or safety.

Turn observations into decisions

After the session, I group observations around the learning question. I look for moments of confusion, unexpected workarounds, missing context, and assumptions that the prototype exposed. I avoid treating every preference as a requirement. A request may point to a deeper need, but I still need to understand the situation behind it.

I use a decision record with three parts: what I observed, what I think it may mean, and what I will do next. Possible outcomes include continuing with the concept, changing the flow, testing a different assumption, narrowing the audience, or stopping the idea. Stopping is a useful result when the evidence shows that the problem or approach is not strong enough to justify more investment.

I connect prototype learning with other product work. A design sprint for PMs can create a focused timebox for turning a question into a testable artifact. I use wireframing for product managers when the structure of the interface is the main subject, and usability testing for PMs when I need to observe people attempting a task. A prototype may also expose an assumption worth recording in an assumption-mapping guide.

My bottom line

I use prototypes to reduce uncertainty, not to create the appearance of certainty. I start with a decision, choose fidelity that matches the question, test the riskiest assumption, and keep observations distinct from interpretation. The best prototype is not the one that looks most finished. It is the one that helps me make a better product decision before the cost of being wrong grows.

Next step

For a structured foundation in product discovery, communication, and execution, I use the Product Manager Certification, a commercial Product HQ resource. The Product HQ newsletter shares practical product lessons and frameworks.

Kevin Lee
Kevin Lee
Kevin is a Co-Founder of ProductHQ. He has worked as a VC at Pear Ventures where he invested in and partnered with early-stage founders on product & growth to help them build the foundations of category-defining companies. He has worked as a Product Manager at AltSchool (backed by Andreessen Horowitz, Founders Fund, First Round Capital, Mark Zuckerberg, John Doerr and other exceptional investors). Previously, he was a Senior Product Manager at Kabam (acquired by NetMarble and Fox for a combined $1bn+), where he worked on products through all lifecycles in San Francisco, Vancouver, and Beijing and helped grow one of the company’s products to become the third largest revenue generating product in the company portfolio. In a former life, he worked in Technology Investment Banking at Merrill Lynch. He is also the author / co-author on 10+ gaming patents.