A Valentine’s Day STEM Activity for Kids

Valentine’s Day is the perfect time to learn about one of the most important organs in the body — the heart! Instead of just talking about hearts, let’s become Heartbeat Detectives and investigate how our hearts change when we move, rest, and relax.

This hands-on STEM activity lets kids act like real doctors and scientists by measuring, comparing, and analyzing their own heartbeats.

What Is a Heartbeat?

Every time your heart squeezes, it pushes blood through your body to deliver oxygen and nutrients. That squeezing is called a heartbeat — and how fast it beats is called your heart rate.

Your heart rate changes depending on what you’re doing:

  • It speeds up when you move

  • It slows down when you rest

  • It changes when you feel excited or calm

Let’s find out how!

What Kids Will Learn

  • How the heart responds to movement and relaxation

  • How to measure heart rate using a simple tool

  • How doctors monitor vital signs

  • How to record and compare scientific data

Supplies

  • 3–4 craft sticks (popsicle sticks)

  • Tape

  • Small balloon (optional)

  • Paper clip

  • Stopwatch or timer

  • Paper and pencil

Build Your Pulse Sensor

  1. Stack and tape 3–4 craft sticks together to make a sturdy “pulse pad.”

  2. Tape a small piece of balloon or a paper clip to one end — this helps you feel tiny pulse movements better.

  3. This is now your DIY pulse sensor, just like a doctor’s monitoring tool!

Find Your Heartbeat

  1. Place two fingers on your wrist or the side of your neck.

  2. Gently press your pulse against your pulse pad.

  3. Feel the rhythmic “tap-tap” — that’s your heart working!

Measure & Record

Create three columns on a piece of paper:

At Rest After Activity After Deep Breathing

Step 1 – At Rest

Sit quietly. Count your heartbeats for 15 seconds.
 Multiply by 4 to find your beats per minute (BPM).

Step 2 – After Activity

Do jumping jacks or run in place for 30 seconds.
 Measure again and record your BPM.

Step 3 – After Deep Breathing

Take slow, deep breaths for one minute.
 Measure again and write down your BPM.

Analyze Like a Scientist

Compare your three numbers:

  • Which was highest?

  • Which was lowest?

  • Why did your heart rate change?

Talk about how the heart works harder when your muscles need more oxygen — just like during sports or play!

STEM Extensions

Engineering:
 Try making a new pulse pad using foam, fabric, or cardboard. Which works best?

Math:
 Graph your BPM results to see how your heart changed.

Health Science:
 Discuss why doctors and nurses always check heart rate during exams.

Why This Matters

Your heart works every second of every day to keep you alive. Valentine’s Day is a great time to remember that loving your heart means keeping it strong with movement, rest, and healthy choices.

At Little Medical School, we love helping kids explore real medical science through hands-on discovery — and this activity lets them step into the role of a real medical professional.

Happy Valentine’s Day, Heartbeat Detectives!