This year, I was introduced to a website called Collaborative Mathematics through the math teacher's circle that I participate in once a month. It is a site that puts out a video explaining a really interesting math problems and asks people to solve them and send in videos of how they solved the problem. The challenges are put out once a month by the author Jason Ermer. Jason is a Math and Computer Science teacher in Oslo, Norway.
I really liked the problems and started playing the videos and doing the challenges in class with my students right before a break or when the schedule was crazy. The kids got into them and the discussion was great! I also like it because there isn't a quick answer and it really forces the students to listen to each other and challenge each others' thinking.
The one thing that I have learned after doing a few of the challenges is that my struggling kiddos need some help focusing their thinking or else they will give up. For the last challenge that we tried before spring break, I made the worksheet below and it really seemed to help my struggling students get into the problem and feel on par with those who were getting it faster. I'm including it if you would like to try Challenge #3 with your students and use the worksheet. This challenge is really good for writing rules for arithmetic sequences and pushing it farther into what happens when there is an alternating sequence and how do you write it. But, by far, that isn't the only way to solve this problem! :)