Great textbook that goes over key applied linguistic theories. I actually still use this textbook (5ed) to cite a bunch of my papers. The wording is very easy, and chapters build off of previous chapters ideas. Very easy and decent textbook.
Although it is a great book for understanding how students acquire foreign languages, I expected more strategies that help teachers plan their lessons. Even so, all teachers should read it because the book makes us reflect on our own way of teaching and how to improve it.
A really solid place to start if you want to know about how languages are learned. Goes into a lot of detail, helpful examples, lots of great research is mentioned.