Well Simone, I think our contrasting answers will confuse Pikafu over here.
I am going to disagree with Simone, and explain why, so that Pikafu over here can understand my point of view.
I think you've got it right: You identify the general area -- engineering -- as well as the specific field of interest -- nanotechnology. You do so in a manner that is lively and engaging.
Although you may not yet know what you want to major in, which department or program at MIT appeals to you and why?
^The essay prompt is the reason why. Pikafu may have the general idea, engineering, and the field of interest, but neither of these are departments or programs at MIT. There is no explanation on why either of these is appealing and the reason why also