Exercises: Prototyping: concept and purpose

Define what a prototype is and explain its main purpose in the development of a new product or service.

Distinguish between low-fidelity prototypes (sketches, paper, cardboard) and high-fidelity prototypes (nearly functional), and explain why initial testing is carried out using low-fidelity prototypes even if they "look like toys".

The figure shows three levels of fidelity in prototyping a mobile app, from lowest to highest. Identify the missing intermediate level, marked with '?', and explain what can be validated with it that cannot be validated with the paper sketch.

Classify these prototypes according to their fidelity (low, medium or high) and justify your classification: a hand-drawn sketch of an app's screens, a cardboard mock-up of a lamp and a website with buttons that seem to work but always respond the same way.

A team draws on paper the screens of an app for the neighbourhood library and tests them with five neighbours. List three things it can validate with that prototype (whether the navigation is understandable, whether any feature is missing, whether the service is of interest) and one that it will not be able to validate until it has the real app.

You can do it on paper and send a photo with your answer.

Explain with an example why prototypes save money: compare the cost of changing the design of a piece of furniture when it is still a drawing and when 500 units have already been manufactured.

How do you prototype a service, which is not an object? Explain two ways of prototyping a laundry pick-up service (role-playing it with actors as in a play, running a manual pilot with five neighbours) and what is learned with each one.

Explain what iterating means in prototyping (test, learn, improve and test again) with the example of the design of a folding chair that goes through three versions.

A team wants to create a book-sharing app for neighbours. Before writing any code, they draw the screens on paper and ask five neighbours to 'use' them with their finger. Explain what they can validate in this way (navigation, clarity, interest) and what things they will not be able to validate until they have the real app.

You can do it on paper and send a photo with your answer.

Explain how a service is prototyped, given that it is not a physical object: what techniques allow it to be tested before launching (role-playing with actors, a pilot with a few customers, manual simulation of the service) and give an example of each.

A company spent a year and all its savings manufacturing 5 000 units of a kitchen gadget without showing it to anyone beforehand, and barely sold any. Analyse what process errors it made and what it would have found out with three successive cheap prototypes.

A team wants to launch a plant swapping app between neighbours. Propose a minimum viable product that does not require programming (for example, a neighbourhood messaging group and a shared spreadsheet) and explain which two hypotheses of the model it allows checking.

Design a test session with six users for the paper prototype of an app that organises play dates between dogs: what tasks you would ask them to do with their finger, what you would observe meanwhile and what three questions you would ask them at the end.

A team spends three months polishing a "perfect" demo before showing it to anyone. Analyse the risks of polishing a high-fidelity prototype so much (attachment to the design, cost of changing, learning late) and what the iterative approach would have recommended.

The "Wizard of Oz" technique consists of manually simulating a service that will look automatic (for example, an ordering chatbot actually run by a person). Explain what it is for before programming the automation, which hypotheses it allows validating and what ethical limit should be respected.

When testing the prototype of an ergonomic office cushion, qualitative data (comments, gestures) and quantitative data (assembly time, comfort rating from 1 to 10) can be collected. Explain what each type of data provides and why it is worth collecting both.

An entrepreneurial team wants to launch an anti-theft backpack with a biometric lock and cut-resistant fabric onto the market. They have 2.000 € and 6 weeks before pitching the project to an investor panel. One of the partners suggests directly commissioning a factory for a finished functional prototype for 1.800 €. Critically evaluate this proposal in terms of resource allocation and business risk, and design an alternative three-stage consecutive prototyping plan (specifying the type and fidelity level of the prototype, the learning objective, and the success metric for each phase) that optimizes the available budget.

A startup is simultaneously developing two projects: a mobile app for hospital shift management and an ultralight ergonomic wheelchair. The CTO suggests applying an "evolutionary prototyping" strategy in both cases, arguing that this avoids wasting resources on disposable materials and speeds up development. Analyze the economic and technical suitability of this decision for each of the two projects, anticipate the risks of applying such an approach to the physical product versus the digital one, and propose the most efficient prototyping strategy in each case.

A traditional bakery is considering investing €9.000 in machinery to produce sugar-free wholemeal pastries, but fears that its regular clientele might reject the product due to taste or a price premium. Design a phased, very low-cost prototyping plan in three stages to validate real demand before undertaking the investment. For each phase, you must specify: the hypothesis being tested, the chosen prototyping artifact or experiment, and the exact quantitative criterion that would justify advancing to the next phase or canceling the project.

The coffee shop «La Taza» is evaluating investing in a delivery motorcycle and thermal packaging to offer breakfast delivery in a nearby business park. a) Formulate the two critical hypotheses (one regarding the customer value proposition and another regarding operational feasibility and costs) that determine the idea's success. b) Design two sequential prototyping experiments, from lower to higher fidelity, without purchasing permanent equipment or hiring permanent staff, explaining what key information each will provide. c) Set a quantifiable metric threshold in the second prototype that objectively determines the decision to launch the definitive service or abandon it.

A town council wants to trial a provisional cycle lane before building it permanently: it paints it on the road, puts up plastic separators and measures for three months. Analyse how this trial resembles the prototyping of a product (which hypotheses it validates, what it measures, what success criterion you would use) and what the difference is with testing something with volunteer customers.

A board game publisher has invested €15.000 in manufacturing 1.500 units of a new game after successfully validating it through cardboard prototypes exclusively with members of a veteran strategy club. Upon going on sale in general retail stores, the game is a commercial failure: buyers describe it as cumbersome and complain that the quality of the components does not justify its €40 price. a) Diagnose the methodological validation flaws committed, distinguishing which product dimensions the low-fidelity prototype did allow measuring and which were neglected. b) Explain the sampling bias introduced during testing. c) Design the prior prototyping and testing protocol the company should have followed to avoid this failure.

A company manufactured 10 000 mobile phone cases with a new grip system without prototyping it first, and users complained that the volume button was covered. Analyse the cost of the error in process terms (not only economic: image, returns, wasted time) and design the cheap prototyping plan, with two iterations, that would have avoided it.

The product director of an established home appliance brand argues: «Showing rough or unfinished prototypes to potential customers destroys our brand prestige; we must only test flawless, final versions». Refute this argument from the perspective of enterprise risk management and agile innovation: a) Explain the economic and opportunity cost of postponing testing until the finished product is available. b) Design two operational or segmentation strategies that allow a large company to test low-fidelity prototypes with real users while minimizing reputational risk.