Edward L. Thorndike’s book The Psychology of Arithmetic (1922) is the earliest I’ve seen containing criticism of the visuals in textbook design. I wanted to share three of the examples.
Fig. 47.—Would a beginner know that after THIRTEEN he was to switch around and begin at the other end? Could you read the SIX of TWENTY-SIX if you did not already know what it ought to be? What meaning would all the brackets have for a little child in grade 2? Does this picture illustrate or obfuscate?
Fig. 51.—What are these drawings intended to show? Why do they show the facts only obscurely and dubiously?
Fig. 52.—What are these drawings intended to show? What simple change would make them show the facts much more clearly?