I rarely give extra credit assignments. I have found that allowing students to redo low assignments has been the most educationally beneficial in my classroom. This way, students are working on learning the concepts they need to know for the upcoming test or paper rather than focusing on something only related to the curriculum. The extra credit I give is usually along the lines of positive reinforcement for class participation, or for rewarding students who go beyond the established criteria for a particular assignment. Students may earn A+ passes for rewards for reading above and beyond the AR requirement as well. A+ passes can be used to improve a low homework score to an A+.