Just as you mastered the art of packing the perfect diaper bag, he’s potty trained and headed to preschool. Help him make sure he’s got this one in the bag.Step One: Find the perfect carryall. It should be big enough to hold essentials (a snack, a sippy), but not so large that it weighs him down. Our pick: the handmade cotton and linen messenger bags from Mee a Bee ($25-$40), sized to sling across the chests of scholars ages 3 to 6.Step Two: Leave a paper trail. Ecojot’s latest collection of spiral-bound sketch pads and journals ($4.50-$17) supports the Jane Goodall Institute with collage-inspired cover images of endangered species. But it’s the recycled, unlined paper and heavy-duty back cover that give kids what they need to write and draw.Step Three: Color it in. P’kolino’s art set ($20) is a cornucopia of jumbo markers, triangle and wrapper-free crayons, and hexagonal colored pencils — all designed to fit little hands. So practicing good form is as easy as one, two, three.Looking for the perfect lunch box? Check out our photo gallery.CREATE Youth Arts FestivalWhat: Check out puppet shows, crafts, and more. Why: Get messy making a papier-mâché monster.When: Sat., 10 a.m.-4 p.m.Where: Jefferson-Houston Elementary School, 1501 Cameron St., Alexandria. Info at 703-746-5588. Admission is free.WATCHMorning Concerts for KidsWhat: See what magician Mike Rose has in his bag of tricks. Why: Take blankets and a picnic of PB&Js.When: Thurs., 10:30 a.m.Where: City Hall Concert Pavilion, 31 S. Summit Ave., Gaithersburg (301-258-6350). Admission is free.GAZEMovies on the PotomacWhat: Tote along chairs for outdoor movies on the plaza screen.Why: Superhero flicks could inspire a bit of do-gooding (or couch jumping). When: Thru Sept. 26. Sun., sunset. Where: National Harbor, 150 National Plaza (877-628-5427). Admission is free.Photos: Courtesy of Jacqui Miyabayashi / Mee a Bee; Courtesy of Ecojot; Courtesy of P’kolinoUp to 75% off MLHLynne Hiriak (of Cardigan fame) ups the knitwear ante with ’70s- and ’80s-inspired dresses and sweater tops with color blocks, sequins, and vintage-meets-modern shapes. Take up to 75% off on Swirl.