Turning your idea into a build prompt
You now have one small idea. This lesson turns it into a "build prompt."
A build prompt is what you will paste into Google AI Studio. It needs to be much more specific than a normal chat message. You need to tell the AI exactly what to build, how it should look, and how it should behave.
This is the fourth prompt in the sequence you started in the previous lesson: you brainstormed, you explored variations, you cut the idea down, and now you write the prompt.
The most confident colleague you will ever have
AI will build what you tell it to build, not necessarily what you wanted it to build.
It will ask you questions — but only about the things it notices are missing. Everything else it simply decides for you: how many questions, what happens when a student is wrong, and the unexplained shade of purple. Every one of those decisions is reasonable on its own, and none of them are yours. That is why a clear, specific prompt matters. Say who it is for, what it must do, what it must look like, and what "finished" means, and you get something usable on the first attempt instead of the fifth.
Framework
The CRAFT framework
Five things have to be settled before anyone can write a good build prompt. You are not going to work them out on your own. The prompt further down asks the AI to interview you about each one, in order, one question at a time, and only then to write the build prompt for you:
Context
What do you teach, and what is the teaching situation?
Role
Who should the AI act as while it builds this?
Action
What exactly should it produce for you?
Format
How should the app be laid out, and how should it behave?
Target audience
Who is this for, and what experience should it create for them?
That is the whole framework. Answer its five questions and it has everything it needs to write a specification detailed enough that AI Studio has nothing left to guess at.
The ground rules
What your first app must stay inside
Your idea is settled. These five rules are what you attach to it. They keep the app buildable in one session, and they stop the AI from handing you something that needs a login, a database, or a monthly bill.
One screen
No menus, no tabs, no second page. The whole experience fits in one view.
Everything inside the app
The questions, examples, answers, and feedback are part of the app itself, not fetched from somewhere else.
No sign-ins, no saved data
No accounts, no student records, nothing stored after the page is closed. Students open a link and start.
Nothing that costs money
No other services, and no AI running while students use it. That kind of app bills you every time a student clicks.
Easy to use and easy to reset
Works on a phone as well as a laptop, is easy to read, and can be started again from the beginning.
Notice that none of this names a programming language or a framework. It does not need to. AI Studio decides how to build the thing; your job is to describe what it does and what your students experience.
And one line to stop it growing
Ask an AI for a specification and it will be generous: a settings screen, difficulty levels, a leaderboard, a dark mode. None of it was in your idea, and all of it is work you now have to check. The prompt below ends your build prompt with this line, which is the cheapest thing in Part 1:
Build exactly what is described above and nothing else. Do not add extra features, screens, settings, or options, however useful they might seem. If something is unclear, choose the simplest version of it rather than the more capable one.
Prompt 4 — Write the build prompt
Paste this into the same ChatGPT, Claude, or Gemini conversation you have been using. It will interview you through CRAFT, then write the build prompt for you. Answer its questions in plain language:
"I teach [SUBJECT] to [AUDIENCE LEVEL]. I have an idea for a small teaching app: [PASTE YOUR IDEA], but I haven't worked out all the details yet.
Act as an expert instructional designer. Ask me questions, one at a time, to fill in the CRAFT framework: my Context, the Role you should play while building, the exact Action I need from you, the Format and interactive behaviour of the app, and my Target audience. Do not move on until I have answered each question. If I am unsure of an answer, suggest a simple default rather than adding complexity.
Once you have enough detail, write a detailed 'build prompt' that I can paste into Google AI Studio to generate this app.
In that build prompt, include exactly this: Keep it to one screen, with no menus, tabs, or other pages to navigate to. Everything the app needs, including the questions, examples, answers, and feedback, must be built into the app itself. No sign-ins or student accounts, nothing saved after the page is closed, no connections to other websites or services, no AI running while students use it, and nothing that costs money. It should work on a phone as well as a laptop, be easy to read, and easy to reset and start again.
End the build prompt with exactly this line: Build exactly what is described above and nothing else. Do not add extra features, screens, settings, or options, however useful they might seem. If something is unclear, choose the simplest version of it rather than the more capable one.
Do not name programming languages, frameworks, or libraries anywhere in the build prompt. AI Studio chooses those. Describe what the app does and what the student experiences."
Tip: Answer the five questions quickly rather than perfectly. If you find yourself agonising over one, say "you choose a sensible default" and move on. You can change anything once you see the app running. The one question worth real thought is the feedback: what a student is told when they get something wrong is where nearly all of the teaching happens.
A faster route, if you are short of time
The interview is worth the five minutes, because the questions you find hard to answer are usually the ones AI Studio would otherwise answer for you. But if you are in a hurry, here are two ways to skip straight to a draft and refine it afterwards.
Option A — one draft
"Take this rough classroom idea and rewrite it as a strong prompt I can paste into Google AI Studio. Keep it simple, one-page, and beginner-friendly. Here is my idea: [PASTE YOUR IDEA].
Include exactly this: Keep it to one screen, with no menus, tabs, or other pages to navigate to. Everything the app needs, including the questions, examples, answers, and feedback, must be built into the app itself. No sign-ins or student accounts, nothing saved after the page is closed, no connections to other websites or services, no AI running while students use it, and nothing that costs money. It should work on a phone as well as a laptop, be easy to read, and easy to reset and start again.
End with exactly this line: Build exactly what is described above and nothing else. Do not add extra features, screens, settings, or options, however useful they might seem. If something is unclear, choose the simplest version of it rather than the more capable one."
Option B — three versions to compare
If you would rather see a few directions side by side than commit to one, ask for three at once:
"Give me three versions of this app idea I can build in Google AI Studio: [PASTE YOUR IDEA]. Version 1 should be very simple. Version 2 should be more interactive, with scoring or immediate feedback. Version 3 should be more playful or game-like.
Every version must include exactly this line: Keep it to one screen, with no menus, tabs, or other pages to navigate to. Everything the app needs, including the questions, examples, answers, and feedback, must be built into the app itself. No sign-ins or student accounts, nothing saved after the page is closed, no connections to other websites or services, no AI running while students use it, and nothing that costs money. It should work on a phone as well as a laptop, be easy to read, and easy to reset and start again.
Every version must end with exactly this line: Build exactly what is described above and nothing else. Do not add extra features, screens, settings, or options, however useful they might seem. If something is unclear, choose the simplest version of it rather than the more capable one.
Write each version as a complete prompt I can paste directly into Google AI Studio."
Either way, expect the result to be thinner than the interviewed version. Read it against the example below and add whatever it left out.
What a finished build prompt looks like
This is what came out of that interview for a management accounting app. The headings are the AI's own; what matters is the ground it covers. Notice how little is left to guess at: the number of items, when feedback appears, what it says, whether a student can retry, and how you will know it is done.
Purpose and audience
For first-year management accounting students who can already define fixed and variable costs but hesitate on mixed and step costs. After using this, a student should be able to place a cost in the right category and say why it belongs there.
Core interaction
One cost item is shown at a time. The student chooses one of four categories: fixed, variable, mixed, or step. Twelve items in total, three of each category, always in the same order.
Content
Twelve short cost items written in plain language, for example "Factory rent of £4,000 per month", "Raw materials at £3 per unit", "A supervisor's salary plus a bonus of 2% of output", and "One extra machine hired for every additional 500 units produced". Each item has one correct category and a one-sentence explanation of why.
Feedback and scoring
Feedback appears immediately after each answer, before the next item. If the answer is right, say so and show the one-sentence explanation. If it is wrong, name the correct category, show the explanation, and add one line on why the chosen category does not fit. An answer cannot be changed once submitted. A running score is visible throughout, in the form "4 of 7 correct". At the end, show the final score and a review listing every item answered incorrectly with its correct category and explanation. A "Start again" button resets the score and returns to the first item.
Layout and visual design
One screen. A clear heading at the top, the cost item in large text in the middle, four large category buttons below it, and the running score in a corner. Calm and plain: a white background, one accent colour, generous spacing, no images or animation. Comfortable to use on a phone held in one hand.
Accessibility
Text large enough to read on a projector at the back of a room. Strong contrast between text and background. Colour is never the only signal: feedback always carries words as well, such as "Correct" or "Not quite". Every button can be reached and pressed using only a keyboard.
Technical constraints
Keep it to one screen, with no menus, tabs, or other pages to navigate to. Everything the app needs, including the questions, examples, answers, and feedback, must be built into the app itself. No sign-ins or student accounts, nothing saved after the page is closed, no connections to other websites or services, no AI running while students use it, and nothing that costs money. It should work on a phone as well as a laptop, be easy to read, and easy to reset and start again.
Definition of done
A student can work through all twelve items on a phone, see feedback after each one, reach a final review of everything they got wrong, and press "Start again" to begin from the first item with the score reset to zero, without ever leaving the screen or being asked to sign in.
Build exactly what is described above and nothing else. Do not add extra features, screens, settings, or options, however useful they might seem. If something is unclear, choose the simplest version of it rather than the more capable one.
Before you move on
Read your build prompt once and check that a colleague could tell, from the prompt alone, what a student sees when they get an answer wrong and what would make you call the app finished. If either is missing, ask the AI to add it. That paragraph is what you paste into AI Studio next.