The Common Core was created in 2009 and is meant to even the playing field by giving every state a universal set of standards to measure learning and comprehension. The program is incentivized with federal grant money that is given to states that implement the standards.

The goal is to help students understand that subtraction problems are essentially asking you to measure the distance between two numbers. It's a method of teaching math that relies more on theory than rote memorization.

While this method supports the Common Core's goal of putting more of an emphasis on critical thinking, it can be a headache for parents who grew up on rote learning and were taught completely different ways of doing math. These parents may have trouble helping their kids with their homework.