Another tool for creating self grading quizzes has come to my attention. Flubaroo was the first I found and it works great. Another that works equally as well for me is Super Quiz. Like Flubaroo this add-on uses Google Forms to build your quiz. Its a great tool. Grades your quizzes and sends the results directly to the students. There area several videos on YouTube that you may find useful.
Here are two videos you can use to help you utilize Superquiz. I hope you find them useful.