What your Preschooler Will Learn:

Air and water don't occupy the same space

What You Will Need:

A large bowl, bucket or small plastic pool

Water, enough to fill your bowl, bucket or pool

a small, clear cup

What To Do:

Fill up your bowl or bucket with water.

Ask your preschooler what is in the cup. (Air)

Have your preschooler slowly lower the cup into the water, keeping it even with the water. Notice bubbles come out and the water occupies the same space.

Continue to lower the cup until it's completely submerged within the water, keeping a hand on the cup so it doesn't float away. Ask your preschooler if there is still air in the cup.

Have your preschooler tilt the cup a little bit. Does the air come out? What about if you tilt it in another direction? Does air come out?

Take the cup out of the water and drain any water of out of it. Ask your preschooler what it's full of?

Now have your preschooler quickly put the cup into the water, again keeping it even with the water. What happens? Does more air come out or less? What happens when you tilt the cup to the side? Does a big or a little bubble come out?

Now try tilting the cup and lowering it into the water. Does an air bubble get caught again, or does the cup completely fill with water?

Continue to let your preschooler play wit the cup and water to see what happens.

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Helpful Tips for Parents

• Use correct scientific vocabulary from the start: observe, predict, experiment, hypothesis, result, evidence. Children absorb vocabulary in context without explicit teaching.

• Always ask "What do you think will happen?" before running an experiment. Prediction is the core of scientific thinking, and preschoolers' predictions are always worth hearing.

• Repeat experiments multiple times. Reliability — the same result happening consistently — is a key scientific concept, and repetition gives preschoolers the proof they find satisfying.

• Outdoor science (nature observation, weather tracking, garden study) is as rigorous as lab science and has the added benefit of physical activity and environmental connection.

Frequently Asked Questions

What everyday household materials are best for preschool science?

The essential preschool science pantry: baking soda, white vinegar, cornstarch, salt, sugar, food coloring, dish soap, and water. These materials enable: acid-base chemistry (baking soda + vinegar), non-Newtonian fluids (cornstarch + water = oobleck), color mixing (food coloring), surface tension (dish soap), crystal growing (salt and sugar), and density experiments (sugar solutions). Beyond kitchen supplies: magnets, a flashlight, a magnifying glass, and ice are the other essentials. The best science lab is an accessible kitchen shelf.

How do I build a child's science confidence when they get frustrated by unexpected results?

"Unexpected" is the word to use rather than "wrong" — in science, results that don't match predictions are the most interesting. "The result was different from what we expected — that means we discovered something! Let's figure out why." This reframe makes the unexpected result a success rather than a failure, because it produced a question worth investigating. Science confidence is built by treating all results as valid data, never as failure.

Related reading: See also our garden science guide and our weather science for more ideas on this topic.

🎓 Skills Your Child Will Develop

• 💬 Science Vocabulary — Science introduces children to precise vocabulary — observe, predict, hypothesis, dissolve, absorb, transparent — that dramatically expands language range and supports the academic vocabulary children need in school.
• 🔬 Scientific Method — Even a simple experiment teaches the predict-test-observe cycle that is the foundation of scientific thinking — and preschoolers who internalize this process approach problems with genuine scientific confidence.
• ⚖️ Cause & Effect Understanding — Seeing that one action reliably produces a specific result builds the logical framework children use in mathematics, reading (one event causes another in stories), and everyday reasoning.
• 😌 Patience & Delayed Gratification — Experiments with delayed results — growing plants, watching crystals form, tracking weather — teach children to wait for outcomes rather than needing immediate feedback, a skill that predicts academic and life success.

With this fun and easy preschool science experiment, your preschooler will learn that air and water can't occupy the same space as they have fun playing with water on hot summer afternoons.

Questions to Ask Your Child

Use these open-ended prompts to extend the learning during or after the activity:

• "What do you think will happen before we try it?"
• "Was your prediction right, or did something surprise you?"
• "Why do you think that happened?"
• "What would change if we tried it with something different?"
• "Can you think of a place in real life where you've seen this before?"
• "What question does this make you want to answer next?"

There are no right or wrong answers to any of these questions. The goal is to keep the conversation going, model curious thinking, and give your child practice putting their experience into words.