In my class I grade by points. Each assignment given will be worth X number of points.
For example, if students are given a worksheet with 10 questions, the assignment will be worth 10 points. For each correct answer, students will receive a point (on some assignments, students will be able to receive half credit or, in this case .5 points).
Classwork/homework counts once. Test/quizzes count twice.
Extra credit: On the left hand side of this page, you will see a link called Ways To Improve My Grade. This is where students can find ways to earn extra points to add to an assignment.