If you have a mad scientist on your hands, you probably know it. These are the kids who flick the light switches on and off, trying to figure out how they work, the ones who dismantle your alarm clock or obsessively collect and categorize rocks, shells, coins – even toys or cars.

Whether your preschooler seems like a born scientist or you'd simply like to nudge her to explore her world, here are some ideas for encouraging young da Vincis.

Use what you have on hand to bring science to life

You don't have to spend a penny. Water, ice, steam, soil, bubbles, magnets, shadow, air, wind, and light can provide hours of discovery. Preschoolers can also experiment with everyday ingredients like baking soda, vinegar, food coloring, and plastic containers. Stumped for ideas? Look online at places like Science for Preschoolers and Science Sparks.

Explore the science of everyday things

Cooking is a great way for preschoolers to see science at work. Things burn, boil, change color and texture, rise and fall, separate and mix. Take a nature walk and examine the plants, trees, leaves, footprints, and creatures along the way. Investigate the science behind art, like what happens when you mix colors.

Try outings with a science twist

Visit science museums, natural history centers, zoos, and discovery play spaces, especially if they have hands-on activities for small children. These field trips let your child try projects you don't have the equipment, expertise, or space to handle at home. Besides, someone else gets to clean up the mess.

Look for science classes or camps

Many natural history museums and summer camps have science courses for preschoolers. Museums may offer weekday morning or afternoon classes; summer camps may be weeklong and include a science theme, along with time for free play. Popular topics for preschoolers include creepy crawlies, dinosaurs, and chemical concoctions.

Veer into the nonfiction section of the library

Your curious child may like books on reptiles, weather, or trains. Look, too, for guides to doing science experiments at home. The Magic School Bus series is a big hit with many kids curious about how and why things work.

Let magazines and TV fuel her interest

Magazines like National Geographic Kids, Your Big Back Yard, and Wild Animal Baby teach preschoolers about animals, water, stars, and more – all in a way they can relate to. And nature documentaries and science-related TV for preschoolers, like Sid the Science Kid on PBS Kids, bring these things to life in a way that books and magazines just can't do.

Spring for a preschooler-style science kit

Toy stores and museum shops often have age-appropriate options. You can also find them online at sites like Steve Spangler Science. Think a butterfly net or bug catcher for your naturalist, test tubes for your chemist, or blocks and other construction toys for little engineers. For the compulsive collector, hardware stores sell plastic containers with multiple drawers perfect for categorizing shells, rocks, and crystals.

Embrace experimentation

Often, curious preschoolers don't need any prodding to turn their home into a laboratory – just the time, space, materials, and supervision to safely do their thing.

What you can do is rein in the urge to nag about making a mess – science is a messy venture. Lots of science projects can be conducted outdoors. When inside, cover any surfaces you're worried about – then make cleanup part of the project.

Follow your child's lead

Your job is to expose her to lots of science-related subjects and let her pick and choose. Maybe your 2-year-old is consumed with bugs but has no interest in other animals. That's fine. Introduce other topics but respect your child's right to focus on one interest.

Expand your child's horizons through her pet project

Say your 4-year-old is crazy about dinosaurs. Find creative ways to incorporate them into music, art, drama, and movement. This way you can use your child's obsession to expose her to a range of activities.

Read books and sing songs about dinosaurs, do art projects about them, visit museums to see the skeletons, go on a dinosaur dig in a sandbox for dinosaur "bones." Use toy models to make footprints in clay, and act out dinosaur stories with her tyrannosaur and triceratops stuffies.

Resist the urge to set the agenda

Kids with a knack for science often don't respond well to direction, preferring to do their own thing. That's how she learns. Your job is to provide the props and materials and then let your child get busy.

A good rule of thumb: Offer assistance if asked. Otherwise, it's best to stay out of it.

Avoid both lavish praise and correcting mistakes

At this age, it's better to focus on the process and discovery rather than the result. Some of the best science breakthroughs come when things don't quite go according to plan. So encourage your preschooler to try new things and assure her it's fine to get things "wrong" (provided her way of doing things is safe, of course.)

Make observations about what you see, or ask your child what she's doing and what happened as a result. Try "Why do you think there were a lot of bubbles?" instead of "I think you used too much vinegar in your volcano."

Watch your little scientist carefully

Don't let your child mix substances (even seemingly harmless ones) until you've verified there won't be an adverse reaction. A quick peek in a science textbook or a Google search should do the trick in most situations.

Kids who like to experiment need specific rules for safety. Remind kids never to put substances in their mouths, noses, or eyes.