I've just read Michelle Worgan's post on fossilization which I find really awsome in particular her practical ideas. I leave the LINK here because it's worth reading!
I'm quite fan of visual aids to get students react and act. Actually, I've used visual indicators to get the students focus on their mistakes and after reading this article I've redesigned them to fit Michelle's ideas on getting the students focus on their errors.
Who can use the lollipops?
Teachers to assess or point out the students' errors.
Students to assess peers.
Here you have how the lollipops look like:
Notice I've added a code on top of what each lollipop means.
Download them here if you wish, they are ready to print and cut up, and if you use them, I'd love to know how they work for you :)