Explaining a data model is always a challenge, because we like to think that they are clear when we make them, but it is important to also remember that our job serves a wide variety of people in the company. I like to approach this situation by finding out what confuses people the most, then stepping through that part of the model. Once they believe they are getting it, I ask them to explain how that part fits with the rest, so I can hear that they are understanding and discussing it. As we go, if there is anything in the model that they missed or start to misinterpret, then I help guide them back.