Harness the natural curiosity of kids with one of these engaging STEM challenges. We’ve rounded up a few kid-tested, parent-approved projects you can set up and launch in a jiffy, to inspire your budding engineer at any age.

Preschool

Marshmallow construction: All you need are a bag of soft treats and some toothpicks to build a neighborhood of towers and houses, right on your tabletop. Tip: Stash these in a zip-close bag and you have something to keep little hands busy while you’re waiting at the restaurant, the doctor’s office or a sibling’s sports match. Variation: How about toothpicks and cut up fruit? How about plastic toys and play dough?

Build a car: At this age, what’s more delightful for kids than designing their own toy? You bring the LEGO Bricks (or DUPLO), and they bring the inspiration and imagination to build the ride of their dreams. Bonus: Get on the floor and together you can build a city for their cars, complete with roads, ramps, bridges and homemade tunnels.

Ages 6-8

Build a raft: Gather up everyday objects for a raft “design studio.” You can shape a sheet of aluminum foil into a boat hub, use styrofoam cubes, cut apart old beverage bottles and milk cartons, paper shapes and glued together craft sticks. Test their sea-worthiness and see how much they can carry.

Get vertical: Try the vertical challenge and use LEGO Bricks and other construction materials to design and test a marble run. For starters, we’ve rounded up a few ideas. (With a little planning, it’s the perfect play-date activity.)

Ages 9-12

Showstopping projects: They’re getting older, so maybe their interests are more likely to turn toward screens and joysticks instead of an exciting afternoon in Mom’s kitchen science lab. But … they may have science projects to complete, so you’ll still have an “in” for creating and building. Here are a few showstoppers we’ve blogged about in the past. Look to the battles of medieval times and design a catapult or trebuchet, or you can exert “maximum effort to accomplish minimal results” with a zany Rube Goldberg machine.

Get slimed: Forget the concoctions of glitter and contact lens solutions. What you really need is to whip up this batch of really cool magnetic slime. This requires specialty ingredients, which puts it firmly into the bigger-kid category. You’ll need to add iron oxide powder to the mixture to make it magnetic, and to make it move with the power of magnetic force, you’ll also need a set of neodymium magnets.