The teacher's command of his class is total. "Which one is the whole number?" he asks crisply. "Is it seven over three, or is it four?"
An off-hand and off-colour remark by Barack Obama may have signalled a decision by his campaign to go nuclear on Mitt Romney's shifting ideological track record.
One of the requirements? Travelling on a plane once used by U2 on tour.
Barack Obama attempted to seize back the political initiative on Tuesday by abruptly switching to a new, positive strategy for the final stretch of the White House campaign after dominating the third and final presidential debate.
President Barack Obama's claims that massive military spending cuts due to kick in next year "will not happen" caught foes and supporters by surprise during Monday's final presidential debate.
Mitt Romney's more attentive supporters may have been surprised to hear him outline a strategy to combat Islamic extremism that sounded awfully like the nation-building increasingly out of favour with Republicans as costly and ineffective.
Mitt Romney raised Republican hopes of an election comeback with a spirited and aggressive performance that forced Barack Obama repeatedly onto the defensive in the first presidential debate.
A trip to McDonald's, a photo shoot on Red Square, and a chummy meeting with one of his biggest fans – it's all in a day's work for Facebook's chief executive, Mark Zuckerberg, who met Dmitry Medvedev, the Russian prime minister, on Monday during a visit to Moscow.
Just after his inauguration, President Barack Obama made a pledge: to cut the nation's $1.3tn deficit in half by the end of his first term.