1. This Kids Rockclimbing Class — incorporating basic climbing knowledge with bouldering skills — might be proof that it's never too early to start pushing oneself to the limit. Brooklyn Boulders, 575 Degraw St. 9 a.m. $45.
2. At Transit Tots, youngsters age 2-5 get a chance to hear stories and play games while learning about a marvel of early 20th century engineering called the New York City subway system. New York Transit Museum, Boeurum Place and Schermerhorn Street. 10:15 a.m. Free with admission.
3. So you think you can dance? Well, it all depends in Lucy Guerin's Untrained, which features a professional dancing duo teaching a pair of newbies how to bust a move onstage. BAM Fisher, Fishman Space, 321 Ashland Place. 7:30 p.m. $20.
4. Test that noggin' over a few microbrewskies at Trivia Night with the Brain Machetes aka David Smithyman and Josh Guarino. Halyards, 406 3rd Ave. 8 p.m. Free.
5. Alternate side parking rules are in effect in most of the city, except for Brooklyn Community Boards 13, 15 and 18 and Queens CB 14.