In Module 2 you tapped every part of the context window: system prompt, chat history, your message, and nothing else. That picture just became the most practical thing in this course.
If the AI needs your material, put it in the window, deliberately. That's all an upload is. Attach a file and the app pours its text in alongside your question; the model reads it the same way it reads your message. No mystery, no telepathy. Watch the contract make the journey.