In the world of kiddie must-haves, stacking blocks top the list. It’s a rite of passage to figure out how to build ’em up (and knock ’em down). Inspire towering greatness with a set of custom Big, Little Girl’s vintage-style stacking blocks. The American-made, solid maple blocks are distressed, hand painted, and decorated to order with nontoxic paints. Choose from 22 colors and four themes inspired by the turn-of-the-century (the last one), retro ’50s, mod ’60s, or groovy ’70s. They’re perfectly sized to help little hands build sky-high structures. And lasting memories. Available online at biglittlegirl.biz. DIVE Ocean Detectives What: Kids ages 5-12 and parents explore the mysteries of the deep sea. Why: Get a clue. When: Sat., 2-3:30 p.m. Where: New England Aquarium, Central Wharf, Waterfront (617-973-5206). GO Treehouse Shakers What: West African stories, dance, theater, and music in a fundraiser for the Watertown Family Network. Why: Be a social climber. When: Sat., 10 a.m. Where: Watertown Middle School, 68 Waverley Ave., Watertown (617-926-1661). WONDER Magic Ark Children’s Series: the Magic of Bonaparte What: Mesmerizing interactive show with comedy, illusions, and tricks. Why: You’ll be spellbound. When: Sun., 2 p.m. Where: Striar JCC, 445 Central St., Stoughton (617-965-5226).