BRIC offers free two-hour media classes at various Brooklyn Public Library locations, which provide a general introduction to new ways to use digital media as of 2015. The Brooklyn Public Library also offers free English for Speakers of Other Languages, or ESOL, courses two days a week at its various branches.
The Brooklyn Public Library system also hosts various other events and workshops, most of which are offered free of charge. You can find anything from creative writing workshops to Spanish language conversation groups in the Programs & Events section of its website.
If you're interested in learning the techniques of sewing, the Brooklyn Sewing Collective offers a great environment to learn the craft at no cost. The courses meet every other Wednesday and provide both instruction and materials for free. You can stay up to date with future sessions via the Brooklyn Launch Pad mailing list.
Many yoga studios in Brooklyn offer free introduction sessions and operate on a pay-what-you-can basis. For example, Yoga for the People in Greenpoint offers yoga classes for a suggested donation of $5. This studio is open to walk-ins and also offers yoga mat rentals for $1.
NYCMeditation.org offers free meditation classes in Brooklyn, Queens and Manhattan. The classes are taught by experienced meditation students and are suitable for beginners and experienced meditators alike. To hear about future sessions, fill out the contact form, and check "Brooklyn" in the list boroughs.