I guess “studying” would be a good word: it's close enough to “reading”, while also having an educational connotation and no expectation of being a linear process.

Although I'd encourage everyone to consider “reading” already as non-linear: see e.g. https://www.cs.cmu.edu/~mblum/research/pdf/grad.html :

> READING: Books are not scrolls. Scrolls must be read like the Torah from one end to the other. Books are random access -- a great innovation over scrolls. Make use of this innovation! Do NOT feel obliged to read a book from beginning to end.