http://www.sheppardsoftware.com/grammar/grammar_tutorial.htm
Learn Grammar and the Parts of Speech with this tutorial.

http://www.sheppardsoftware.com/grammar/verbs.htm
Smack the robots displaying verbs

http://www.funbrain.com/whichword/index.html
In each sentence, decide which homophone should be used.

http://www.starfall.com/

For younger students just learning to read.

http://pbskids.org/

Practice your spelling and improve your ability to read and write.

http://www.drgrammar.org/

This site is designed for older students of to learn about grammar and word choice.

http://www.spellingcity.com/

Vocabulary and Spelling City entices you to practice with games, quizzes, and flashcards.

https://www.websiteplanet.com/blog/talking-aloud-talking-allowed-watch-write-make-sure-right/

A visual guide to help with learning about homophones.