Educators often assume implicit knowledge. I fondly remember my first day at IT school. We went into the PC room and everyone should do some basic research on

Educators often assume implicit knowledge. I fondly remember my first day at IT school. We went into the PC room and everyone should do some basic research on the C programming language. We didn't even had to program anything. And a guy sat next to me on the PC and asked me how to switch it on. Then he asked how he even would find, let alone use a search engine. Math and programming books are prone to such issues. Especially math books assume, you still know everything you learned in school.