This file contains 5 sorting mats (Joining, Separating, Part-Part-Whole, Additive Comparison, and Equal Groups.) There are three pages of problems to go with each mat. Problems include Start Unknown, Change Unknown, and Result Unknown. Numbers used are 30 or less. I have used these in my minilessons to introduce problem types and strip diagrams. I have also used these in stations where all of the pieces are cut apart and I put symbols or letters on the back so the students can check their work. Thanks for looking at my product. Please leave feedback because I always want to grow and improve in my work!