Willie Shubert, left, taught this spring’s Knowledge Commons DC class "The Universe is a Salad: Texturescapes," with Laura Kwong. (Photo by Mark Gail/The Washington Post)

Knowledge Commons DC, a “free school” program, connects the intellectually curious with the thing Washington is swimming with: highly-educated people with lots of useful — and occasionally totally esoteric — skills. Knowledge Commons starts a new “semester” every few months, and registration for the June session opens Friday at 6:30 p.m.

Volunteers just sign on to teach classes on subjects they’re interested in. When it comes to subject matter, the quirkier, the better: The upcoming session includes courses in the Python programming language; using herbs and tinctures for your health; hemming jeans; knowing thyself; and parsing the language of Shakespeare.

Organizers believe it shouldn’t cost anything to learn, so students aren’t on the hook to pay (though they might be prodded to contribute a few dollars for materials in culinary-themed classes). The group holds sessions in donated spaces: The Hirshhorn has hosted a beat-making class, last semester’s course in the art of salad-making was taught at a Washington hostel, and a Jedi and Trekkie “fandom” event was at the Georgetown Public Library.

The next Knowledge Commons is June 2-30. Registration opens Friday at 5 p.m. For the full listing of classes, visit Knowledge Commons’ Web site.or just get a feel for the group at its Spring Fling at 6:30 p.m. Friday at Old City Green, Ninth and N streets NW. Tickets to the fundraising event are $15; courses are free.