MAC Recreation Rooms. You want your own mat. M-F, most sections between 12 and 2 p.m.; call for specifics.

Note that certain classes require advance registration and are always liable to change, so calling ahead is wise. Partners are optional.

Boston Ballet Studios, 19 Clarendon St., Boston. 695-6950, ext. 267. $10.

Green Street Studios. 185 Green St., Central Sq. 864-3191. $10-12.

The Dance Complex 536 Mass. Ave. 547-9363. $8-12. http://cambridge.zami.com/dancecomplex.

Harvard-Radcliffe Ballroom Dance Club. Classes start the 23rd and run for about four weeks. $20. http://www.hcs.harvard.edu/~hrbdc.

Malkin Athletic Center (MAC). Classes started on the 10th. 495-2219. Aerobics info: 495-8683. FREE (yoga $5).

Radcliffe Dance Program, Agassiz House, Radcliffe Yard. Register ASAP at the Dance Office in the basement of Agassiz House. M-F 1-5 p.m. $45-80.