I wish I had these resources when I was in school. I was studying EE back in the late '80s. I had a textbook with maybe two worked out examples for each concept. The answers to the odd-numbered homework problems were in the back, but just as a number. So if I worked out a long problem and got, say, 5 as an answer, and the answer in the back was, say, -5, I had no real way of knowing if I made a mistake somewhere, or if the answer in the back of the book was incorrect. Working in groups was discouraged as a kind of cheating because you were supposed to do your own work. The professors weren't that interested in teaching because they felt they were there more to rank us. And the teaching assistants were mostly foreign-born with limited spoken English skills.