He’s talking about textbooks.
This article looks at the move toward digital textbooks, but I don’t think it goes far enough.
“I want our teachers to have the best materials available, and with digital textbooks, we could see the best lessons taught by the most dynamic teachers,” said John A. Roach, superintendent of the Carlsbad, Calif., schools. “But they’re not going to replace paper texts right away.”
There’s only one substantive reason given in the article not to switch this instant:
Not every student has access to a computer, a Kindle electronic reader device or a smartphone, and few districts are wealthy enough to provide them. So digital textbooks could widen the gap between rich and poor.
I am still trying to figure out how textbooks have held on as long as they have, and whether there are any pedagogical reasons for keeping some of them.