Vocabulary.com
A terrible website which naive teachers use which allows you to create a list of vocabulary to study and quiz yourself over. It will allow you to "master" all but one of the words, then force you to sit through hours of questions you already know the answers to so that you can finally answer the last question about the last word so that you can "master" it.
I stayed up until 2:00 AM mastering all the vocabulary for homework. Fuck vocabulary.com for wasting my time on words I already know.