English Grammar 101

This free website has 15 modules of multiple lessons (and reviews) on nouns, pronouns, verbs, sentence parts, adjectives/adverbs, prepositions, conjunctions/interjections, verbals/phrases, clauses, capitalization, punctuation, and troublesome words. For a fairly reasonable price, teachers can purchase full access to create assignments and track progress, and their students can take pre- and post-tests for each module.