This was the first time I tried having the students self evaluate on individual challenges, but it actually worked really well. Before turning in their card, they had to show me their completed challenge, as well as how it worked and what happened when variables were manipulated. They could then turn in their card and move on to the next challenge. This gave me the opportunity to quick check in with groups as they were working (as I was moving about the classroom) and help groups talk through any problems they were having working together so they could make sure everyone was actively participating. It provided a great way for those who felt like they were being excluded to safely voice their thoughts and be part of the success of the group.