What your Preschooler will Learn from this Preschool Biology Experiment

Where their heart is (in the middle of their chest)

What a heart sounds like

That exercise or fear speeds up a heartbeat

That taking a few deep breaths will slow it down

Basic counting

What You'll Need for this Preschool Biology Experiment

An adult's heartbeat (probably yours!)

A paper towel tube

A timer

What To Do

Step one: Have your preschooler put their hand on their chest so they can feel their heart beating.

Step two: The adult should take some deep breaths and focus on relaxing their body.

Step three: Put one end of the paper towel tube against the adult's chest, and have your preschooler put the other end against their ear.

Step four: Set your timer for a prearranged amount of time, somewhere between fifteen and thirty seconds. Start the timer and have your preschooler count the number of heartbeats until the timer goes off. If your preschooler is having difficulty counting, have your adult find the pulse in their neck or wrist and count with your preschooler.

Step five: After the timer goes off, your adult should stand up, do some jumping jacks or run in place or a minute. You're trying to get the adult's heart rate to go up.

Step six: Start your timer and have your preschooler listen to the heartbeat again. Have them count the beats until the timer goes off.

Step seven: Have your adult take some deep breaths and calm down. Again start your timer, have your preschooler listen and count the number of heartbeats until the timer goes off.

Step eight: Have your preschooler try to scare the adult so the adult's heartbeat increases again. Once again have your preschooler listen and count the number of beats.

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Comments from Readers

Hi! I'm Theresa Halvorsen, the preschool science and nature writer for Preschoolrock.com. I have twin boys and am blown away by their fascination with preschool science and how the world works around them. I am always looking for fun and simple science activities so preschoolers can learn about science and the natural world. Please contact me with any suggestions, ideas or questions you have about this site.

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.

• Accept wrong predictions gracefully — "Interesting! The result was different from what we predicted. Why do you think that happened?" Models scientific resilience.

• Connect science observations to real-world applications: "This is why bridges are built this way" or "This is how your body does that." Application makes science relevant.

• Science fear is learned, not innate. Preschoolers approach science with natural confidence — protect that confidence by keeping science joyful and low-stakes.

Frequently Asked Questions

How do I make science experiments safe for preschoolers?

Keep experiments to food-safe or food-grade materials whenever possible: vinegar, baking soda, cornstarch, salt, food coloring, and dish soap cover most preschool science. Always supervise hands-on experiments. Establish and enforce the rule: "We only put things in our mouth that adults say are safe." Keep experiments away from eyes — vinegar and salt water sting. Wash hands after all experiments. A pair of toy safety goggles adds a "scientist" identity bonus while providing real protection from splashes.

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.

Related reading: See also our nature walks guide and our color mixing 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.
• 📏 Early Math & Measurement — Measuring ingredients, comparing quantities, and observing size changes connects science directly to mathematical thinking — making science experiments some of the richest early math experiences available.
• 🏗️ Engineering Thinking — Testing structures, materials, and designs to see what works develops engineering intuition — the practical understanding of forces, materials, and design that underlies all physical construction and problem solving.
• 📝 Recording & Documentation — Drawing what they observe, recording measurements, and noting results gives children their first experience of scientific documentation — and connects science to literacy and numeracy in an authentic context.

When your preschooler goes to the doctor, the doctor listens to their heart with the stethoscope. With this fun and easy preschool biology experiment, your preschooler can actually listen to a heartbeat without needing a stethoscope. They'll also learn that our heartbeats speed up or decrease depending on many factors