This worked really nice as a practice activity today, by my criteria of : the kids talk to each other, have ways to figure out if they're correct, and have ways to find their mistakes if they're not. I like when I can spend my time helping kids who need it and asking and answering meaningful questions, and don't have to hear "Is this right?" over and over.
The students got in groups of four, and each group got a total of 16 problems. Four pieces of paper with four problems each. The papers were different colors.
The students completed one problem on each page. So they all worked on one, rotated papers, worked the next one, etc. These guys even coordinated their calculators.
The paper color corresponded to the difficulty of the problems, which I let them know.
When all four problems were complete on a page, they added up their four answers. I posted the sums on colored index cards.
So if they check their sum and it's correct, great. But the best dialog started if it wasn't correct. Because first, they had to figure out which out of the four answers was wrong. And is it smart to start over and re-do the problem? Not in this case, since they were solving equations. It made much more sense to plug the answers in and see which one didn't work. Then they could start error-checking their work, which is great practice in itself.
The topic was solving exponential equations by changing the base, though this could work for anything. The document with the problems is available here. Enjoy!