So she says maths, we say math, but I think we can both agree there are some pretty great ideas coming from Jo Boaler and YouCubed math at Stanford University. The newest resource YouCubed has released is a set of classroom posters, including posters on Norms, Discussion, Growth Mindset, and the Value of Mistakes among others.
Check them out here: https://www.youcubed.org/resource/posters/