You can see it right there in the illustration: one double-sided piece of blank note paper (preferably lined or even done in graph paper format with half-centimetre squares, very lightly ruled, so that learners could either write notes and/or easily create grids, diagrams, maps, etc.) for each double page spread in the coursebook. Perforated as well, so that it could be removed if needed.
You'll have to forgive me if I've missed something really obvious about relative costs involved in doing this (surely it doesn't make the book more expensive than the cost of coursebook plus blank note pad?), but it is the one thing that has constantly struck me as being a plain simple good idea.
And almost every single class of adult learners in particular that I've taught in the past decade has agreed that this would be ideal. The content in their books has become increasingly tiny in font and claustrophobically packed in, with nary a piece of white space anywhere to take notes that they will be able to make sense of. And once learning activities and notes become segregated into completely separate books, it creates a a risk of a mild sort of learner schizophrenia.
I'm dead sure I couldn't have been the first person to suggest it...
So why haven't we seen this in educational (ELT in particular) coursebooks yet?
What am I missing?
=D
