When I looked through, it seemed clear, well structured, colorful, full ... He gave really want to work. This is part of an investment of 26, it is not nothing! After working with, I advice you not to buy it! First of all these are being SHEETS and not the full course (I did not notice), over there a lot of errors especially in maths exercises and even parts of recalls !! I have not yet finished studying but I'm already more than 10 errors! So I sent a message to the editor no answer. Made the right choice!