Possibly it could contain the address at which you could access the workbook online, and maybe print it out, although even such a trivial inconvenience could still be a barrier to a lot of people.
Bothering to access the workbook online could be a practice test of instrumental rationality in and of itself.
Bothering to access the workbook online could be a practice test of instrumental rationality in and of itself.
And if you explicitly frame it as such, the entire book has primed them to pass this particular test.