These task cards include 12 multiple choice, student-tested problems. (Answer Key is first page).
When I use these in my classroom, I give each group one set of problems and assign a "discussion leader" to read the problem. I also give each group member a pinch card with A, B, C, or D. Once the card is read aloud to the group, someone keeps time for 2 minutes of independent thinking. Then each student shows their thinking using the pinch card. I require that each student explain his or her reasoning to the group. The group comes to a collaborative answer after hearing each explanation.
Each student writes down the answer, and the substitution that proves the answer.