If you are teaching English as a second language, this site, "English Grammar Quizzes in Javascript", will be good practice for your students. It contains tons of computerized little quizzes to test their knowledge of the English Grammar. It is all multiple choice and the student gets immediate feedback after he or she answered. It covers many concepts of the English grammar including nouns, verbs, pronouns, punctuation, misplaced words, prepositions, participles, etc. It comes with five level of difficulty : easy, easy to medium, medium, medium to difficult and difficult. All the quizzes are written in JavaScript, so they should run easily in your web browser.