Check: sources, cross-checking, limits of web search

This lesson is still being tested: it improves with learners' feedback. If something is unclear, it is the lesson that needs fixing, not you.

By the end of this lesson, you will be able to

ask “Where does this information come from?”, and judge the answer;
open a cited source and check that it really says the same thing;
cross-check important information against an official source;
use your assistant’s web search, knowing what it does not guarantee.

Why it matters to you

In module 1, you saw the AI’s pitfalls: made-up facts, dates, calculations, overconfidence. This lesson gives you the defense, in three reflexes that take two minutes. It is the fourth step of the method: CHECK. It doesn’t apply to everything: only to what matters, when a mistake would cost you time, money or a failed procedure.

Before you start


You need	Your assistant, free account, and your error logbook from module 1
Cost	€0
Duration	40 minutes
Reminder	The questions in this lesson are practical; they say nothing about you

Understand it in 3 minutes

An answer can come from three places, and it is not checked the same way.

Where the answer comes from	What it is worth	Your reflex
What the model learned	Often right, sometimes outdated or made up, with no page to open	Ask where it comes from, then check what matters yourself
A document you provided	Often reliable, but the AI may misread or fill in	“Show me the exact passage from my document”
A web search	More up to date, with links	Open the links: does the page exist? Does it say the same thing? When is it from?

Be careful with the answer to “Where does this information come from?”. Without web search, the AI can cite a plausible source that does not exist: this is the made-up facts pitfall. A source only counts if you can open it.

Web search helps, but does not settle everything. Claude and ChatGPT can search the internet, even with a free account, and then give links to their sources.

But OpenAI’s help page says it itself: results and citations can be incomplete, outdated or incorrect. It advises opening the source, looking at its date, and preferring an authoritative source when accuracy matters.

Cross-checking means comparing two independent sources, one of them official when possible. Asking a second AI is not cross-checking: an AI is not a source.

The source that counts, depending on the subject:

For	Go to
An administrative procedure in France	service-public.gouv.fr, the official website for information and administrative procedures (in French)
A price, an offer	The seller’s official page, shown in your country
A software feature	The publisher’s official help, looking at its date
Your health, a legal problem, your money	A professional (module 1, lesson 2)

Do it together

1Step 1: The question, without search

Without searching the internet: what documents are needed to replace the lost ID card of an adult who has a valid passport, in France? Tell me where your information comes from, and how recent it is.

Look at the answer: it may be right in broad terms, but the AI cannot show you a dated page. For a procedure, that is not enough. If you don’t live in France, you can ask the same kind of question about your own country instead, and use your government’s official website in the next steps.

2Step 2: The same one, with web search

On Claude: search often happens by itself when the question is about recent information. According to Claude’s help page (24/10/2026), you can also turn it on with the + button at the bottom left of the conversation window, then “Web search”, or simply write “Search the internet” in your request.

Depending on the version of the interface, there may be no button: Claude searches when it is useful.

On ChatGPT: search can also start by itself. To ask for it, OpenAI’s help page (24/10/2026) points to the tools menu (“View all tools”, then “Search”), or the / key typed in the message box, then “Search”.

Then send:

Now search the internet, on the official website of the French administration, and give me the exact link to the page that answers this.

3Step 3: Open the source

Click the link and answer three questions:

Does the page exist, and is it really about your question?
Does it say the same thing as the AI’s answer? Compare the list of documents, point by point. (For the ID card, the official page (in French) distinguishes several cases: valid passport, expired passport, no passport. Compare with the case in your question.)
When is it from? Look for the update date, at the top or bottom of the page.

4Step 4: Check at the source, and have it corrected

Compare the answer from step 1 with the official page. If there is a difference, the official page wins. Tell the AI:

The official page says [what you read]. Correct your answer, and tell me what was wrong in the first one.

Your turn

Three questions from your life where a mistake would cost you something: a schedule, a price, a rule, a deadline, a procedure.

Ask each question to your assistant.
Open the source it cites, and answer the three questions from step 3.
For at least one of the three, check against the official source from the table; if you have time, cross-check with a second independent source.
If the AI got it wrong, note the case in your error logbook, adding how you spotted it: the source you opened, the detail that was off. This story will help you in lesson 6.

Resources to download

My error logbook: the logbook from module 1, to complete with your checks.

Check your work

It worked if:

for your 3 questions, you opened and read the source, without stopping at the link;
at least one answer was checked against an official source;
you can say, for each one, whether the AI was right, half right, or wrong;
if it got it wrong, your logbook contains the case and how you spotted it.

Common mistakes:

believing a link is proof: many people never open it;
“cross-checking” with a second AI;
forgetting the date: a page that was right three years ago can be wrong today;
checking everything, all the time: keep this reflex for what really matters.

Keep it and pick it up later

Add to “My requests”: “Search the internet: where does this information come from? Give me the exact link to the page and its date, and tell me if you did not open it.”
Your error logbook now says, for each mistake, how you spotted it.

Going further

optional

On a free account, web search uses up your usage limit. Claude’s help page says so: searching and reading pages count toward limits that reset every five hours, and a long article given by its link can use up a good part of it. Ask for search when the information needs to be recent, not for everything.
Both assistants can use your approximate location, deduced from your IP address, for a local question (“a restaurant near here”).
With ChatGPT, web search rewrites your question and may send it to partner search engines, using your memories if memory is on (lesson 5): no personal data in a search question.

New words

5 words explained

Word	What it means
Source	A page or a document that you can open, date and attribute to someone
Citation	The link or reference the AI gives to support a sentence
Cross-check	Compare two independent sources, to see whether they say the same thing
Official source	The source that counts on a subject: the administration, a software publisher, the seller of an offer
Web search	The feature that lets the assistant search the internet before answering

Still to verify: the exact on-screen labels for web search in both interfaces (taken from the official English help pages, not from a live test).