What have you learned about the textbooks we are using for this course?

I have learned that some professors actually use the textbooks that you purchased for the class. I got one of mine from my daughter that took this same class on campus last Fall (NOT same instructor). The book was still in the wrapping and bran new. She told me that the teacher never required them to use it, she ran copies in class and used power point to get them the info. I am amazed, I don't think I can write anything without the reference material, pdf files, the internet and emailing my instructor, many many times. I still wonder how .14 of an inch appears out of nowhere.