Will Smith turned lots of heads in London last week when he appeared at a school assembly and rapped the theme to the Fresh Prince of Bel-Air ... seriously.
The rapper / movie star visited St. Martin-in-the-Fields High School; he was invited by Streatham Member of Parliament Chuka Umunna.
Umunna joined him on the Fresh Prince rap. Check it out:
Smith was in the UK to watch his Jaden open for Justin Bieber's tour ... Will was not there when JB tried to beat the f--k out of a photographer.
Both Smiths costar in sci-fi blockbuster After Earth June 7.