The Office of the First Lady issued this statement yesterday:
I took a look at “gap year” here. The bottom line is that it originated as a British term in the 1980s, and has been in common use in the U.S. since the early 2000s.
More important, good on ya, Malia, and have a brilliant year.
notoneoffbritishisms.com 
As a Brit, while it’s interesting to see a Briticism in those two sentences, I count no less than three apparent Americanisms!
(‘fall’ is of course obvious. ‘Class of [year]’ seems like an Americanism to me; it’s not a usage I’ve ever heard in the UK. And have you already discussed ‘school’? In the UK that applies only to primary and secondary education, i.e. up to age 18, and never overlaps with ‘university’ or ‘college’.)
Referring to college as “school” is common in U.S.–e.g, “Where do you go to school?” I have a feeling it’s relatively recent, but don’t have any evidence to back that up.
“Good on ya, Malia, have a brilliant year”
Australian and British expressions? I love it. It all makes perfect sense to me!
Also most of my colleagues in the UK call it Medical or Dental school
Medical school and dental school are the preferred terms in the U.S. as well.
I agree…have a fab gap year, Malia!
“School” has historically been used in the UK in relation to higher education establishments that were not themselves universities – hence “Medical School”, “Art School”, “London School of Economics” etc. But virtually all of these have now either become universities in their own right, or been absorbed into a university. However the usage still persists – but in this context “school” it is always qualified by an appropriate adjective. Using “school” on its own is a reference to pre-university education.
A number of UK universities group various departments and faculties into “schools” for administrative purposes – so for example my alma mater has six schools, each of which comprises a number of faculties and other institutions (so, for example the School of Technology comprises the Faculty of Engineering, the Faculty of Business & Management,the Faculty of Computer Science & Technology, the Department of Chemical Engineering & Biotechnology and the Institute for Sustainability Leadership). In turn, each of the faculties may be divided into Departments. Note also the difference in the use of “faculty” between BrE and AmE. In BrE it refers to a subject division of the organisation, not the individuals.
Gap years are becoming increasingly popular in the U.S.A., partially as a result of service organizations making scholarships available to lower income students and to universities recognizing the benefits to their incoming students, as reported in last night’s interview on the PBS NEWSHOUR with Florida State University’s Joseph O’Shea. http://www.pbs.org/newshour/bb/why-more-teens-like-malia-obama-are-taking-a-gap-year/
I wonder, what did Americans call gap years before the early 2000s? Assuming they took them back then – the link hah15 posted says last year the number jumped 20%, so working back maybe few did them ten years ago.
A Brit, I took a year off after my A Levels in 1975, but as our host notes that was before the term gap year (or indeed “gap yah” for posh people) was current in the UK, and it was simply called “a year off”, as I recall; maybe some people called it a year out. (In part of my year off I went to the USA for three months with Camp America and worked in a summer camp in North Carolina.)
Per Google’s Ngram, the term “gap year” had some very low usage in mid-19th century Britain, but it may well have had some entirely different meaning, I don’t know. By the same source, I infer that it started being used in the U.K. with the current meaning circa 1970 and in the U.S. about 5 years later. Then, it started taking off on both sides of the Atlantic around 1990.
I don’t know of any my classmates who took a gap year, but my alma mater sponsored junior years abroad at institutions like Heidelberg and the Sorbonne (nickname for the University of Paris, 1806–1970). Had I the means, I would have dearly loved to have taken a gap year myself. Although the term wasn’t in use at the time (1962) the concept certainly was.
How about “internship”? That word mystified me when I first heard it (in England) but now it is common.
“Internship” here typically means an actual job of sorts with or without pay, in one’s anticipated eventual profession. Since it’s a sponsored learning experience, regular hours are usually expected to be kept and a living allowance or a small stipend to cover such may be paid. Many internships span the summer or cover a single semester.
“Gap year,” on the other hand, historically suggests, at least in my mind, a year in which one is free to explore the world or take an adventure in some part of it entirely on one’s own or with a few friends and virtually free of supervision, which is why it’s been seen in the past as reserved for the well-to-do.
If you pronounce it ‘gap yah’ you’re a bit rah (slang for posh).