Have students practice their grammar by finding the grammar mistakes in the senteces on these worksheets. Another fun thing to do after students have completed it is to have them write their corrected sentence on the board and write their name by it. As you go over the sentences, if they did the corrections and properly fixed the sentence, they can earn a piece candy or a bonus point on the quiz. If they missed a correction or didn't correct something that they should have, other students in the class can volunteer to change the sentence correctly in order to "steal" the bonus points or candy. Sometimes, when you go over something, students do not bother to pay attention, but adding this incentive really keeps the other students engaged and on task.