The early bird gets the day care slot. Claim yours today when enrollment begins for Little Green Tree House, the eco-conscious child care center and preschool opening this spring in the West Loop. The outdoors-themed spot (check the real fallen tree in the lobby) accepts kiddos ages 6 weeks to 5 years. Wooden toys, organic cotton crib sheets, and cloth diapers give infants reason to coo. Older tots will harvest an outdoor vegetable garden and make nontoxic art projects (soy crayon drawings, red clay sculptures). The mezzanine-level tree house doubles as a stage upon which every child can be a star. Don’t wait to worm your way in. Little Green Tree House, 118 South Ashland Avenue, between Monroe and Adams Streets (312-492-9876). To download enrollment forms, go to littlegreentreehouse.com. EXPERIMENT Chicago Public Schools Student Science Fair What: More than 300 kids demo wacky and wonderful projects (making Mentos explode in carbonated soda, testing cooling/heating effects of electrical currents). Why: They’ve got chemistry. When: Fri., 1-3:15 p.m.; Sat., 9:30 a.m.-3:15 p.m.; Sun., 11 a.m.-noon. Where: Museum of Science and Industry, 57th St., at Lake Shore Dr. (773-684-1414). REGISTER Summer Theatre Adventure Camp What: Children 8-14 hone their acting and storytelling chops at Adventure Stage Chicago’s summer camp. Why: It’s heaven for little hams. When: Sign up now for camp July 27-Aug. 7. Where: Online at adventurestage.org. Camp held at 1012 N. Noble St., at Augusta Blvd., Wicker Park (773-342-4141). LISTEN The Storybook Mom What: Yarn spinner Nili Yelin entertains tots with interactive stories, riddles, dance, and music. Why: Fun leaps off the page. When: Every Mon., 10:30-11 a.m. Where: Little Threads, 2033 W. Roscoe St., at Seeley Ave. (773-327-9310).