Simple Science Experiments Safe for Preschoolers

You don’t need a fancy lab to bring science into your preschool room. You already have everything you need: curious kids, soap, water, a little food coloring, and a willingness to get a tiny bit messy. Science at this age is really about wondering, watching, and talking together—not perfect results or big explanations.

Below are six easy, low-cost, and safe science experiments perfect for preschoolers. You can do them in small groups, during centers, or as part of your circle time.

1. Magic Milk Color Explosion

This one is a big “wow” with very little prep.

What you need:

• Shallow dish or tray
• Milk (enough to cover the bottom)
• Food coloring
• Cotton swabs or toothpicks
• Dish soap

What to do (short version):

• Pour milk into the tray.
• Add drops of different food colors around the milk.
• Dip a cotton swab in dish soap and gently touch the milk.
• Watch the colors swirl and “dance.”

What kids are learning (in kid language):

• “When I add soap, something changes.”
• Colors mix, move, and spread.
• Cause and effect: “When I touch it, something happens.”

You can keep language simple: “The soap is pushing the colors around.”

2. Sink or Float Tub

This is a classic that preschoolers will happily repeat all year long.

What you need:

• Clear bin or large bowl of water
• A mix of safe objects: plastic animals, blocks, spoon, cork, crayon, pom pom, etc.

What to do:

• Let children pick an object.
• Ask: “What do you think—will it sink to the bottom or float on top?”
• Drop it in and watch what happens.
• Sort objects into “sinks” and “floats” on a tray or towel.

What kids are learning:

• New vocabulary: sink, float, heavy, light.
• Predicting and testing ideas.
• Comparing objects and describing what they see.

3. Dancing Raisins (or Rice)

Bubbles plus patience equals a really fun mini show.

What you need:

• Clear cup or jar
• Clear soda (like lemon-lime) or water with baking soda and vinegar
• Raisins or uncooked rice

What to do:

• Fill the jar with soda, or with water plus a spoon of baking soda.
• Drop in a few raisins or some rice.
• Watch them sink, then rise, then sink again as bubbles attach and let go.

What kids are learning:

• Things can move without being touched.
• Bubbles stick to objects and help them rise.
• Observing changes over time (“It was at the bottom, now it’s at the top!”).

You can just say: “The bubbles are giving the raisins a ride.”

4. Walking Rainbow (Paper Towel Color Walk)

Beautiful, quiet, and perfect for a science center.

What you need:

• 6 clear cups
• Paper towels
• Water
• Food coloring (red, yellow, blue)

What to do:

• Line up 6 cups in a row.
• Fill cups 1, 3, and 5 with water; leave 2, 4, and 6 empty.
• Add red to cup 1, yellow to cup 3, blue to cup 5.
• Fold paper towels into long strips and connect each cup like a bridge.
• Over 30–60 minutes, water and colors “walk” into the empty cups, making new colors.

What kids are learning:

• Colors mix to make new colors.
• Liquids can “travel” through paper.
• Patience and checking back over time.

Tell children: “The color is walking up the paper and into the next cup.”

5. Oil and Water “Mini Lava Lamp”

This is a gentle, easy version of a lava lamp that preschoolers can safely watch.

What you need:

• Clear bottle or jar
• Water
• Vegetable oil
• Food coloring
• Optional: a small piece of effervescent tablet (if allowed in your program)

What to do:

• Fill the jar halfway with water.
• Add a few drops of food coloring and stir.
• Fill the rest with oil, leaving a little space at the top.
• Let children watch the layers separate.
• If appropriate, drop in a small piece of fizzy tablet and watch the colorful blobs rise and fall.

What kids are learning:

• Oil and water don’t mix.
• Colors can stay in one layer.
• Rising and falling motion as gas bubbles move.

Language you might use: “The oil wants to float on top of the water.”

6. Nature Scientist Walk

Science doesn’t have to stay indoors. A simple walk can become an experiment in observation.

What you need:

• Small baskets, bags, or egg cartons
• Paper and crayons (for rubbings or drawing)

What to do:

• Go outside and invite children to collect “nature treasures” (leaves, small sticks, rocks, flowers, etc.).
• Back inside, sort by size, color, or texture.
• Use magnifiers if you have them, or just “look closely” with your eyes.

What kids are learning:

• Comparing and categorizing.
• Using senses to explore the world.
• Building vocabulary: rough, smooth, bumpy, spotted, tiny.

A Quick Note on Safety

Because you’re working with preschoolers, a few simple guidelines help keep everything safe and stress-free:

• Always supervise closely, especially with water, small objects, or anything fizzing.
• Use taste-safe or non-toxic materials where possible—but remind children, “We look with our eyes, not our mouths.”
• Keep experiments short, simple, and repeatable rather than big and complicated.

For printable preschool science activity ideas and planning tools, you might like a platform such as brightwheel, which shares ready-to-use classroom activities and resources for early educators: https://mybrightwheel.com/blog/science-activities-for-preschoolers

From an accounting partner’s perspective, we love these kinds of low-cost, high-impact activities. They make your program feel rich and engaging without large supply budgets—and that’s great for both learning and your bottom line.