Find the development imbroglio at ground zero childish? Redirect your gaze to Chinatown, then, where some kid-focused planning is progressing in a very mature way. The nonprofit design firm Hester Street Collaborative is rebuilding Sara D. Roosevelt Park — that slab of concrete and turf running from the Manhattan Bridge to Houston Street — by using art exercises to determine what kinds of new fields and seating areas the local kids and elderly need, and the designers celebrated their progress last week at their second annual Chinese New Year party. Collaborative director Anne Frederick says she's still building consensus and won't show off designs yet to avoid ruffling feathers — Larry Silverstein, are you listening? — but her group and the schoolkids it trains have already made a mark. There's talk of making the sidewalk-stenciled names and kid-painted historic signs it set up last spring at Allen and Grand into the basis for a permanent upgrade of the midblock malls. —Alec Appelbaum