An itty-bitty mind is a terrible thing to waste. So is an empty spool of yarn, a pen barrel, and fabric swatches.Good thing local nonprofit Trash for Teaching is devoted to salvaging both with its new Junkit Kits.What you get: a ten-pound box of assorted castoffs from local industries (clean and safe, of course) to use as educational tools. Dump the contents on the floor and let kiddies (ages 4 and up) get busy sorting, patterning, and identifying objects by size, color, shape, and texture. The box comes with a general how-to guide, but really there are no rules when it comes to free play.If anyone tells you differently, that’s plain rubbish.Available online at trashforteaching.org. MAKEFun FirecrackersWhat: Kiddos craft safe, patriotic decorations to let freedom ring. Why: Avoid the emergency room. When: Sat., 11 a.m.-3 p.m.Where: Lakeshore Learning. For store locations, go to lakeshorelearning.com.ENJOYChildren’s Hour What: Catch free weekly concerts, sing-alongs, and puppet shows all summer. This week it’s Aaron Nigel Smith and the Fundamentals Band. Why: Ideal for getting past hump night. When: Thru Aug. 30. Wed., 7-8 p.m.Where: Levitt Pavilion, 85 E. Holly St., b/t N. Raymond & Fair Oaks Aves., Pasadena (626-683-3230).U-PICKBlueberriesWhat: Follow the blueberry trail to Underwood Family Farms before the season ends.Why: True blue. When: Thru mid-July. Daily, 9 a.m.-2 p.m. Where: 5696 Los Angeles Ave., at Somis Rd., Somis (805-386-4660).