What Is Understanding/How Is It Measured?

We have been talking in E2T2 class for about 15 minutes (at this moment) on "What is understanding?" and "How is understanding measured?"  Whether you are in the E2T2 cohort or not, please leave your comments on what you believe regarding these two questions. Please answer openly.  I don't need an answer that reflects what the state or federal standards say about what understanding is or how to measure it.

Mastering Low-Level Content raises some good questions...