For the Teacher: Why is a deep understanding of this concept important?
What do students need to understand? What misconceptions do students have and how are they developed? What further learning and readings might be helpful?
For the Teacher: Stop saying
Sometimes we say things in order to help students do the math rather than understand the math. Those statements can create misconceptions and confusion when the statements no longer hold true at later grades. What might those statements be for this concept? Why are they an issue? What could be said instead?