My family uses Grammar Ninja. We love it and it is super easy. Each section is timed.Here is the Link http://www.kwarp.com/portfolio/grammarninja.html.
On Grammar Ninja, you are given sentences and a goal to find a part of speech. At the end of each level it tells you what your Ninja rank is.
I encourage you to use it! It is also completely free. We do it for grammar over the summer and love it.
We love it and hope you do to.