An obvious first choice is "the language." We don't have an official language, though we should. If you are to be part of the society and not in an isolated huddle, you need to speak English.
Another obvious body of knowledge is the history and general culture, and the basics of how the economy and government work, and what is expected of citizens--and what is expected of guests. Immigrants who learn these things from American movies are in for surprises.
Our local cultures do not all assume the same courtesies, but we should try to assemble a set, with explanations ("How are you?" is not requesting your medical history, give up your bus seat to someone infirm, etc). Now that I think of it, quite a few of our citizens never learned some of these...
How to arrange this is another problem. But for the moment just think about what you want an immigrant to know (and practice as needed) to be able to fit in.
Instructions on how to thrive (e.g. ignore the ubiquitous advertisements and save your money) may overlap with this curriculum somewhat.
A student coming for college will probably be associating with an unrepresentative group of people, and not see or understand what happens in the background to provide his education. Best be explicit upfront about what is acceptable and what is not.
I suspect that I'd get very different answers to this from painters at the union hall and from the HR staff at Target.
