My guess is that this is related to spatial memory. A lot of memorizing techniques somehow use space to anchor memories on; eg the old Greeks used to walk down the city’s main street while rehearsing speeches, and anchoring topics spatially onto the buildings.
A textbook is not exactly a street you are walking down, but it does have a certain physical place for every topic, and our brain can anchor it there, like „let me see, differential equations are in the last third.. ah there is this other topic, I know that diff equations come right after that“.
A textbook is not exactly a street you are walking down, but it does have a certain physical place for every topic, and our brain can anchor it there, like „let me see, differential equations are in the last third.. ah there is this other topic, I know that diff equations come right after that“.