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Module 3 · Talking to AI: prompting · Lesson 17 of 32

Prompt mistakes and how to fix them

9 minFree GenAI course · BeginnerLesson 3.5By Saket Bhatnagar

Researched and drafted with AI, reviewed and edited by Saket Bhatnagar.

In short

  • Most bad AI answers come from a handful of fixable prompt mistakes, not a “dumb” model.
  • The big ones: a vague ask, missing context, too many tasks at once and no format.
  • Diagnose the symptom, fix one thing, try again. Prompting is a quick feedback loop.
Soon

Video lesson · coming soon

Prompt mistakes and how to fix them

Lala, your AI mentor, will walk you through this lesson in a short animated video. Until then, everything is here to read and try.

  1. 01 “Write my project report”
  2. 02 Think like a family doctor
  3. 03 Symptom, cause, fix one thing
  4. 04 The big four mistakes
  5. 05 Let’s play prompt doctor
  6. 06 Say what to do, not what not to do
  7. 07 Play the game, then meet your data

It is 1 am in a hostel in Lucknow. Zoya’s final-year project report is due on Monday. She types “write my project report” into an AI chat app and gets three pages about “the transformative power of technology in modern society”. Nothing about her project, a smart irrigation system.

She messages her friend Ishaan: “This AI is useless.” Ishaan reads her prompt and laughs. “It’s not useless. It has no idea what you built.” Fifteen minutes later, with a better prompt, she has a solid outline that is actually about her project.

Bad answers have causes you can find

In this module you learnt what a good brief looks like: role, context, task, example, format. You saw examples steer style, steps improve reasoning and schemas fix the shape. Almost every bad answer is one of those pieces missing or broken.

The prompt doctor’s loop

Look at what is wrong, find the missing piece, change one thing and compare. Repeat until the answer is good enough.

Diagram connections:

  • Disappointing answer to Name the symptom
  • Name the symptom to Find the cause
  • Find the cause to Fix one thing
  • Fix one thing to Try and compare (run again)
  • Try and compare to Name the symptom (still off?)
  • Disappointing answer: Too generic, too long, wrong facts or wrong shape.
  • Name the symptom: Say in one line what is wrong, like “it ignored my budget”.
  • Find the cause: Which piece is missing: context, format, one clear task?
  • Fix one thing: Change only that piece, so you know what helped.
  • Try and compare: Run it again and put the two answers side by side.

The eight most common prompt mistakes

Here are the mistakes that cause most bad answers, each with the symptom you will notice and the fix. Keep this table nearby the next time an answer disappoints you.

Prompt mistakes, their symptoms and their fixes
MistakeSymptom you noticeFix
Vague askGeneric, could-be-anyone answerSay exactly what you want, for whom and for what use
Missing contextWrong assumptions about you or your situationAdd the facts only you know: your level, your project, your limits
Too many tasks at onceSome parts skipped, the rest shallowSplit the job into steps, one task per message
No formatA wall of text, or the wrong lengthState length and layout: “5 bullets”, “a table”, “under 100 words”
Only saying what not to doIt does the thing anywaySay what to do instead: “under 80 words” beats “don’t be long”
Clashing instructionsAn odd answer that half-follows bothRemove the clash, or say which rule wins
Asking for facts it can’t knowConfident, made-up detailsPaste the source and ask it to answer only from that, or say “I don’t know”
One endless chatIt forgets rules from early onRestate key facts, or start a fresh chat with a short summary

The last two link back to module 2. A model only knows its training data and what you put in the prompt, so it fills gaps with fluent guesses. And a long chat can push your early messages out of the context window, so the model truly no longer sees them.

Prompt chaining is the cure for “too many tasks”. Instead of one giant request, Zoya asks for an outline first, checks it, and then asks for one section at a time. Each step is small enough to get right, and she can correct course early.

A fix in action: Zoya’s project report

Here is the prompt Zoya started with. It has four of the mistakes in one line: vague, no context, a huge task and no format.

text
write my project report

And here is the version Ishaan helped her write. It is the first link of a chain: an outline she can check before any section gets written.

text
Role: You are a helpful guide for final-year B.Tech project reports.

Context: My project is a smart irrigation system for small farms. A soil moisture sensor sends readings to a small board, which switches a water pump on when the soil is dry. I tested it on a 10 x 10 metre plot near Lucknow for three weeks. Water use dropped by roughly a third compared with fixed-time watering.

Task: Suggest an outline for my project report. Do not write the sections yet.

Format: Chapter titles with two or three bullet points under each. Follow the usual order: abstract, introduction, literature review, design, results, conclusion.

Before you answer, ask me up to three questions about anything that is unclear.

One honest note: the AI should help Zoya plan, explain and polish, not invent her results. Her real readings go in the report, and her college’s rules on AI use still apply.

Play prompt doctor

Try it yourselfPrompt doctor: pick the best fixEach patient is a prompt with a bad result. Read the symptom and pick the treatment that fixes the real cause.

Check yourself

Check yourself

Your prompt gives a poor answer. You change the role, the format, the tone and the examples all at once, and it gets better. What is the problem with this approach?

Pick an answer to see why it is right or wrong.

Check yourself

Which prompt avoids the most mistakes?

Pick an answer to see why it is right or wrong.

Remember these three

  1. Bad answers are symptoms: vague asks, missing context, too many tasks and no format cause most of them.
  2. Say what to do instead of what not to do, remove clashing rules, and give the source for facts it can’t know.
  3. Fix one thing at a time and compare, and split big jobs into a chain of smaller prompts.

Questions people ask

Why is AI giving me bad answers?
Usually the prompt is missing something: your context, a specific task or the format you want. The AI fills every gap with a generic guess. Add the missing piece and the answer often improves at once.
Should I start a new chat or keep going?
Keep going while the chat is short and on one topic. If it has become very long, switched topics or started forgetting earlier facts, start a fresh chat and open with a short summary of what matters.
How long should a prompt be?
As long as the task needs and no longer. A quick fact needs one line. A report outline or a cover letter may need a short paragraph of context plus a format. Clear and complete beats long.
Does writing in capital letters or adding “very important” help?
Rarely. Modern models follow clear, calm instructions well, and heavy emphasis can make them over-apply a rule. A specific instruction, like a word limit, works better than shouting.