This site is littered with ads. To make it useable for students you have to buy a subscription. They give you a good deal up front, but then put you on auto renewal for TWICE the amount you sign up for. Be careful because they do not send a reminder and do not give refunds, even if you haven't used the program. As a teacher spending MY OWN money to support my students, I don't appreciate being ripped off by companies like this. Totally disappointed.