Such star cameos are increasingly common as schools intensify their pitches to Hollywood to cast them as film backdrops.
The city's schools feature in scores of recent movies, plus TV shows and music videos. Last month, director Martin Scorsese shot scenes for his forthcoming epic, Aviator (about flight pioneer and eccentric billionaire Howard Hughes), starring Leonardo Di Caprio, at a vacant city school.
Hosting film crews is a nice little earner for schools feeling the pinch from budget cuts. Los Angeles charges crews $1,700 (pound;940) a day - a snip compared with their usual fees - of which 65 per cent goes to the host school and 20 per cent to other schools.