FOR many, January means back to the lecture hall, and not just at colleges and universities. Across New York the backrooms of bars and the main stages of clubs are coming to resemble secret annexes to the Learning Annex — homes to a boom in alternative lecture series that combine the spirit of the seminar room with the atmosphere of speed dating.

Sometimes the matchmaking is purely intellectual, as speakers bring evolutionary biology or astrophysics to first-timers who thought they had just come for the beer. Other times it’s of the more literal kind (though sorry, ladies, the sex ratio doesn’t seem to be any better in nerd circles).

Whether it’s credentialed neuroscientists delivering a solid happy hour on the mysteries of the brain or tag teams of amateurs competing to give the best 15-minute PowerPoint on cephalopod sex or fake alphabets, never has New York (or Brooklyn, anyway) offered so many opportunities to get smart while also getting a bit stupid. Here’s a survey of some offbeat lecture series that let the intellectually curious go back to school, without the homework.

Secret Science Club

Quick-freezing demonstrations onstage and straight-up theme cocktails at the bar are the order of the evening at the Secret Science Club, a five-year-old lecture series that draws overflow crowds to its monthly meetings at the Bell House in Gowanus, Brooklyn.