OpenAI added study mode, "A new way to learn in ChatGPT that offers step by step guidance instead of quick answers."

• Powered by custom instructions written in collaboration with teachers
• Meant to promote active learning, manage cognitive load, encourage curiosity, keep information engaging
• Personalized to user's level
• Quizzes & open-ended questions check knowledge retention
• Toggles on & off during a conversation

They're working on more functionality. Blog has examples & screenshots.

To try it out, choose "Study and learn" in the Tools menu: