In Week 24, we listed the Common Core Standards for Mathematical Practices. The second standard is Reason abstractly and quantitatively.
Mathematically proficient students make sense of quantities and their relationships in problems. They learn to understand the meanings of all the parts of a mathematical problem and can see how the parts relate to each other. They also learn to use symbols to represent a situation and to think about the symbols as separate from the situation. They can create a coherent representation of a problem.
Many problems in CPM have asked your child to reason abstractly and quantitatively. You might ask your child to explain a more involved classwork problem from a recent chapter and have him/her show you how the concepts were represented symbolically. You don’t have to understand all of the math for this to be a useful activity for your student. You will be able to tell if s/he is clear about the ideas by how confidently s/he explains the work.