Related: Fake explanation, Guessing the teachers password, Understanding your understanding, many more
The mental model concept gets used so frequently and seems so intuitively obvious that I debated whether to bother writing this. But beyond the basic value that comes from unpacking our intuitions, it turns out that the concept allows a pretty impressive integration and streamlining of a wide range of mental phenomena.
Large parts of it are isomorphic - At least 3 of the levels seem to closely correspond with chain-, spoke-, and network-type mental models, which I (perhaps regrettably) didn't go into here.