Well, Central America is a region of North America, not its own continent. The dividing line is a matter of opinion, not fact. As a practical matter, there's very little difference between Belize, Guatemala, and the very southern part of Mexico. So it's not wrong to say Mexico is part of Central America. Many Americans do tend to associate Central America with Latin America, which I tend to think is counterproductive. However, given that this conversation exists, I think the term "Central America" is probably counterproductive by itself.