Introducing the MVC pattern along with JavaFX
I'd use the following analogy connecting MVC to a teacher's gradebook.

In the context of MVC, the actual gradebook with a complete record of every student's grade on each assignment is your Model. Students may have their individual grade rendered in the View, but they would never have access to the entire database (for obvious reasons). A Controller, say in a school's learning management system, would select the appropriate grades to display to the specific student. A student could then choose only to render her quizzes or her homework assignments to focus on specifically those grades. In that instance a user action in the View, through say a dropdown, would modify what appears thanks to logic in the Controller.

As with all analogies, it is an imperfect comparison. However, this general concept will be something (nearly) all students are familiar with. 

The iTunes U course on Developing iOS 10 Apps with Swift has a great lecture on MVC. The lecture video and slides are available here.

The image below from Apple also gives a succinct summary of the relationships among the three components.