This book is the book I use in class to check my own grammar knowledge!  It has links to click to better understand certain parts of speech to help back up what is taught in class.  This book is my go-to source!

Yes, this site is really called "Lousy Writer"!  You can click on certain grammar topics and also get some help on developing better writing skills.

Here is a site that has a multitude of grammar lessons to refresh skills or to get a little extra help. 

 This site has games for skill building.  It may seem a bit young for 4th graders but it does have some good practice sessions. 

This site has multiple skills to choose from.  Students click on a certain skill. The site will define the skill, then have a quiz about that skill.  When you're finished, it will show you how you did on each question.  It will even let you click on that question so you can see the correct answer. 

 Students can navigate through the different skills and games.  There are printable stories to check comprehension skills, too.