My class was working through U3L03 today. I was finding it difficult for our class to demonstrate/discuss other group's algorithms. The issue was having the cards visible to their classmates from their seats.
I had some photo magnets in my room for whatever reason and I quickly cut the magnets up into small chunks and then used masking tape to temporarily fasten them to the individual cards. This made it much easier for students to trace the algorithms with their classmates able to see so that they could provide feedback.
I wish I had thought to do this during U3L02, so I figured I would share it here. I thought it may help.