One of the most time consuming parts of being a math teacher is giving student feedback that is constructive and immediate so that they can fix their errors. It can become a lengthy process to give immediate feedback to every student that does not require a lengthy description. One of the ways I have learned to combat that is through create a math grading code. This grading code is a list of 16 shorthand ways to provide immediate feedback to students on common mathematical errors.
You can use the codes to:
Give immediate feedback for independent practice in class
Give feedback for homework problems without having to grade every problem
Allow students to give each other simple, direct feedback when doing peer grading