I collect textbooks as a hobby. It amazes me to no end how the textbooks have changed in the last 120 years. It's especially fascinating to look at math and eng

I collect textbooks as a hobby. It amazes me to no end how the textbooks have changed in the last 120 years. It's especially fascinating to look at math and engineering books from the "Apollo program generation". One thing that sticks out is the huge amount of text that guides the student in building up a deep mental picture and lots of thought-associations in all of these technical books. Somehow after the 60s this approach that is fairly consistent going back a 100 years suddenly is replaced with books that feature a ton of pictures and turn into 'trick and exercise' books until they completely explode with color and small text snippets in the 90s. I have my suspicions that the earlier textual approach might have had its merits. Not sure if anyone has done a comparative study on the effects of organizing text books and their long term effectiveness