How do I make a one-page summary for any UPSC topic (Feynman style)?

Pick one chapter. Close the book. Write what you remember on a single A4 page in language a 12-year-old understands. Mark every gap. Open the book, fix only the gaps. That page — never more than one — becomes your T-30 revision asset. Feynman's technique, weaponised for UPSC.