Online "lessons" explaining various grammar rules and problems. Categorized in levels: Sentence Level, Paragraph Level, and Essay Level, each with subtopics covering specific grammatical concepts.
This wikipedia only uses simple English words and grammar. The Simple English Wikipedia is for everyone! That includes children and adults who are learning English.
Great Source iwrite is a collection of writing resources and support for educators, students in grades 5-12, and parents.
For Educators - Quick access to powerful writing lessons and assessments
For Students - Step-by-step support for completing writing assignments
For Parents - Tips for helping your child become a better writer, thinker, and learner
Drop in a relatively small text (800 words or less), and this little wonder creates graphic organizers, finds vocabulary, builds questions, does pronounciation, prefixes, suffixes.