Exercises: Agile product development and rapid prototyping

1. a) Explain what a prototype is and what it is used for.
2. b) Propose an example of a cheap prototype for each of these three projects: a note-taking app, a new juice flavour, and a trade fair booth.

Why is it said that the first prototype should be "quick and cheap"? Explain what two things are sought with it (learning early, spending little) and what is lost if the first prototype costs $100\ \text{€}$ and takes two months of work.

The figure shows the agile development cycle: four stages that repeat over and over again, but one is covered with a question mark.

1. a) State which stage is missing between the idea and testing, and explain what is built in it and with what materials in a school project.
2. b) Go through the cycle twice using an example: a bracelet stall that changes its design after the first test.

Explain in your own words what agile development is and how it differs from 'planning everything at the start and executing without changes'. Give a school example where the second approach would go wrong (a play that is never rehearsed in full until the premiere).

Define what an iteration is and what is learned in each round of the create → test → learn cycle. Illustrate it with the recipe for the school market biscuits: describe what the team changed (or would change) between the first and the second batch.

Match each prototype with what it tests best: (a) a drawing of the stall on paper; (b) a batch of $20$ units sold at break time; (c) paper screens of the app; (d) a scale model of the stand. Options: (1) whether people really pay; (2) the layout of the space; (3) whether the navigation is understandable; (4) whether the stall idea is explained well. Justify one of your choices.

Explain what 'failing fast and cheap' means and why it is a smart strategy and not a surrender. Give an example of a failure costing $2\ \text{€}$ and one afternoon that can save $50\ \text{€}$ and two weeks at a fair stall.

Name three characteristics of a good quick prototype (cheap, built in hours, designed to learn something specific) and apply them: what prototype you would make to test whether people would buy breakfasts at $1,50\ \text{€}$ at break time, and which specific question it would answer.

The "minimum viable product" is the simplest version that allows you to start learning from users. Define what the minimum viable product of a juice stall would be: what you would include (two flavours, a single size, cash payment) and what you would leave out of the first version (an extensive menu, food containers, app orders), justifying each exclusion.

A wooden keyring evolves as follows: version $1$, an engraved rectangle; version $2$, with rounded edges because it poked into pockets; version $3$, with the school name in colour because customers requested it. Explain what the team learned in each iteration, how they found out, and why they did not design version $3$ directly.

Match each prototyping tool with the stage at which it is most useful: (a) sketch or storyboard, (b) cardboard model, (c) paper screens that are "tapped" with a finger, (d) small real batch to test with customers. Projects: an app, a phone stand, a new snack. Justify the order in which you would use them.

Define the minimum viable product of a 'board game hire service at break times': what you would include in the first week (three games, a sign, a loans notebook) and what you deliberately leave out (a membership fee, an app, $20$ games). Justify each exclusion with what is learned without it.

The juice stall team went through three iterations: v1 with $5$ flavours (endless queues), v2 with $2$ flavours and a single size (short queues, but people asked for mixes), v3 with $2$ flavours plus the 'mix of the day' option.

1. a) Explain what the team learned in each iteration and what data it could observe to learn it.
2. b) Explain why they didn't get v3 right first time and what it would have cost to launch straight away the imagined 'perfect version' from a meeting.

Your team wants to test its book swap app with paper screens. Design the $15$-minute test: which three tasks you ask the user to do (finding a $2$nd ESO book, publishing one of their own), what you note down for each one (time, mistakes, hesitations) and what you would change on the paper if $3$ out of $5$ users can't find the publish button.

One fair team wants 'the perfect stand' and has spent $3$ weeks building it without selling anything yet. Another team sold $20$ badges in the first week with a paper sign and learned which models sell out. Compare both with the language of the topic: which cycle each one follows, what each one is learning and what the 'perfect' team risks on the day of the fair.

Plan the first three iterations of the 'school recycling point' (collection of batteries and old phones): v1, a shoebox and a sign in a single class; v2, three boxes with improved signage after what was learned; v3, a fixed monthly point with weighing and a results board. For each version state which hypothesis it tests (do people bring batteries if the point is nearby?, does the signage change behaviour?) and which metric you would use.

One team spends two months polishing their note-taking app without showing it to anyone: "we will present it when it is perfect". Another team shows a paper version in the second week and makes corrections every Friday.

1. a) Compare the two approaches: what the first risks and what the second gains.
2. b) Explain what could happen on launch day for the "perfectionist" team and why that risk becomes costlier the later it emerges.

Design a three-iteration plan for a school study notes app: what prototype you build in each cycle (paper, digital mockup, minimum real version), how many users you show it to, what you ask them to do, and which metric you decide to improve from one iteration to the next. Explain how you would decide when to stop iterating.

Your team lists six features for the breakfast stall prototype: a menu with $6$ items, pre-orders, card payment, a stamp loyalty card, stall decoration, and delivery to the classroom. You only have $4$ weeks and two people.

1. a) Prioritise: which two features make it into the first prototype and which are left out, using explicit criteria (what is learned with each one and how much it costs).
2. b) Defend why "including everything" would turn the prototype into a delayed product, and what you would say to the teammate who insists that "something would be missing".

The cooperative has fallen in love with its new product: an oat 'energy' shake. They have spent $4$ weeks perfecting the recipe and the packaging without showing it to anyone, and the fair is in $10$ days. You propose selling a trial batch tomorrow at break time.

1. a) Explain which concrete risks the team is piling up by not testing (a flavour people don't like, the wrong size, a rejected price) and why each day without testing makes changing course dearer.
2. b) Design tomorrow's test with less than $15\ \text{€}$: how many units, which two variants you compare, what you note down and which result would make you change product.

'Prototypes are for the insecure: if your idea is good, build it properly from the start.'

1. a) Summarise the argument and detect what it assumes about our ability to foresee what others want.
2. b) Rebut it with the case of the workshop's phone stand: the team's 'well-thought-out' version didn't fit on any school desk, something a $10$-minute cardboard mock-up would have revealed on day one. Draw out the general rule and its limits (when is building properly from the start indeed advisable?).

Your app prototype has $40$ user tests and these data: the 'timetable' feature is used by $38$, 'notes' by $25$, 'chat' by $3$, and the chat button confuses $20$ (they think it is the help one).

1. a) Interpret the data as an agile team: which feature is the core, which one is a candidate for removal and what problem there is with the chat (does nobody want it or does nobody find it?).
2. b) Design the next iteration to resolve the chat doubt (changing the icon and name, measuring another $20$ users) and explain how you would decide to remove it for good if it still isn't used.

Your team has $3$ weeks and a list of $8$ improvements for the breakfast stall: a wider menu, advance orders, two tills, decoration, a loyalty stamp card, coffee for teachers, compostable wrappers and a product photo on the sign.

1. a) Prioritise the improvements with an impact/effort matrix: place each one and choose the three that go into the next iteration, justifying the criterion.
2. b) Explain how you will present the five discarded ones to the team (they stay in the 'car park', they are re-evaluated after the fair) and why knowing how to say 'not yet' is the core skill of agile development.

Design the complete agile process for your class's project over one term: the length of each cycle (weekly, fortnightly), what is built in each of the first three cycles, which test closes each cycle and with how many users, which metric decides whether you carry on as you are or change course, and the end-of-cycle retrospective meeting (which questions you ask yourselves). Defend why that rhythm is better than 'one big delivery' in June.

Topic Challenge. Your mission is to design an agile prototype to reduce domestic electricity spending using real data from Red Eléctrica de España (REE).

1. The challenge: Check the electricity price ($€/kWh$) during peak, flat, and off-peak hours over two days on the ESIOS (REE) website. Define a quantifiable challenge for your household (for example, reducing consumption by $12,5\,\%$ during expensive hours).

2. Agile development: Plan the solution through a rapid cycle. Design a basic Kanban board on a sheet of paper (to do, in progress, done) with four priority tasks to optimize appliance use based on the observed prices.

3. Rapid prototyping: Model a low-fidelity prototype at no special cost (for example, a magnetic traffic light for the fridge or a paper sketch of a family consumption alert app).

4. Testing and proposal: Present the prototype to your family for $24$ hours, collect their opinions in a feedback grid, and write a brief one-page report with the final improvement proposal.

Evaluation criteria:

• Thoroughness in collecting and analyzing official REE data.

• Correct application of the challenge-based approach and agile methodology.

• Functionality and creativity of the low-fidelity prototype.

• Critical integration of improvements suggested by users.