Students are basically copying from textbooks material in an outline form. Usually a few pages. It's not teaching at all but merely parroting what they are reading and then receive a grade essentially upon conformity.
Depends upon the class. Some are different and actually contain targeted questions like these social studies packets...
http://www.fmschools.org/webpages/jworm/files/intro%20to%20social%20studies%20packet.pdf
Is just a random one I looked up.
One of the big problems is that some of the textbooks are ...oh, lets say...a bit biased. Could be said to be indoctrination depending upon political positions of the authors and the packets are often loaded questions.
Interestingly enough, we only see the packet thing in classes like Government, ecomomics and law.