Level 3 was about how you work — iterating, restarting, generating options. Level 4 is about how the AI works. Understanding what it can and can't hold in mind changes everything about how you write prompts.
Reading
Visualiser
Exercise
Quiz
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No memory between chats
Every time you open a new chat with an AI, it knows absolutely nothing about you. Not your name, not what you worked on yesterday, not the preferences you spent twenty minutes explaining last week.
Think of it like a new colleague on their first day. Brilliant — trained on an enormous amount of knowledge. Eager to help. And completely unaware of who you are, what your company does, how you like to work, or what you've tried before.
The new colleague model. You wouldn't hand a new hire a task without any briefing and expect them to nail it first time. You'd spend five minutes getting them up to speed. The AI is the same — except it needs that briefing every single session, because it has no memory of the last one.
This isn't a flaw. It's just how the technology works. The implication: context you don't provide is context the AI doesn't have. Every gap in your brief is a guess it makes for you.
The context window
Within a single conversation, the AI can see everything — but only up to a point. There's a limit to how much it can hold in mind at once. That limit is called the context window.
Picture it as a viewport sliding down the conversation. Everything inside the viewport is visible and actively shapes each response. Everything that has scrolled above the top edge? The AI can no longer see it — which means it's effectively forgotten.
This is why long conversations sometimes feel like the AI "forgot" something. It didn't make a mistake. The information simply scrolled out of the window. The AI isn't holding your whole conversation history — it's working with what fits inside the frame right now.
In practice, most everyday conversations stay well within the window. But once you start using AI for long, complex tasks — research, document editing, extended planning — this becomes something you need to manage deliberately.
Interactive
Drag the slider to scroll through a long conversation. Watch what the AI can — and can't — see.
Start of conversationSeeing messages 1–5End of conversation
Scroll down to see what happens as the conversation grows longer.
What this means for you
Two practical rules that follow directly from understanding the context window:
Recent context is the most powerful context. If something matters — your role, a constraint, a preference — say it again near where it's relevant. Don't assume the AI is holding it from message two of a twenty-message thread.
Long threads need resets. When a conversation has gone on long enough that earlier context might be dropping out of the window, it's often better to start a fresh chat with a clean, comprehensive brief — rather than continuing in a thread where the AI may have lost its early instructions.
The briefing habit. Experienced AI users treat context like a resource. They front-load it at the start of a conversation, repeat what matters when it's relevant, and know when a thread has gone stale. The next three lessons in Level 4 are all about building that habit deliberately.
Exercise
Test your mental model
Read through this 10-message conversation, then answer four questions about what the AI would — and wouldn't — still know by the end of it.
At message 10, would the AI still know that the user is a primary school teacher?
At message 10, would the AI still know the user asked for "no bullet points" at message 2?
If the user opens a new chat tomorrow, will the AI remember any of this conversation?
The user's most recent message (message 10) asks for a lesson plan. Would the AI use the "Year 4, age 8–9" context from message 1?
Knowledge check
Three quick questions
1. What is the context window?
2. You mention your job role in message 2 of a very long chat. By message 40, the AI seems to have forgotten it. What most likely happened?
3. What's the most practical implication of the context window for how you write prompts?
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XP Earned
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Next: Lesson 11 — Front-loading context
Now you know what the context window is. Next you'll learn how to use it deliberately — setting up conversations so the AI performs better from the very first response.
You understand how AI memory works 🧠
Most people use AI for months before realising this. You know it now.