Which AI assistants have a study or learning mode, and how do I turn it on?

ChatGPT and Gemini each have a mode that teaches instead of answering. In ChatGPT it is study mode: type @study, pick Study from the + menu, or open chatgpt.com/studymode, on any plan including Free. In Gemini it is Guided Learning, under More tools in the text box, and it adds diagrams, YouTube videos and quizzes. In Claude Code, the Learning output style leaves small pieces of code for you to write, and in the Claude app you can ask in plain words to be taught rather than told. Start by telling it your level, the topic and your exam date. Each can still slip into handing you the answer or get a fact wrong, so ask for a hint instead when that happens and check anything important against your textbook.