Evidence-based curriculum for ages 2-8

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STEM Activity for Kids: Exploring the Human Heart


Understanding how the heart works is a great way for children to learn more about their bodies. This hands-on STEM activity allows kids to explore how the heart beats to pump blood through the body, creating a visual and interactive way to grasp the concept of the circulatory system.

What You’ll Need for the Exploring the Heart Activity:

  • Glass jar
  • Small empty plastic water bottle (with cap)
  • Bendy straws
  • Ballon
  • Tape
  • Rubber bands
  • Water
  • Red food coloring
  • A push pin

Instructions for the Human Heart Activity

Step 1: Gather Your Supplies

Make sure you have all the materials ready. Set up a clean workspace on a flat surface to make assembling your “heart” easier.

Supplies needed to make a STEM project of the human heart for young children.

Step 2: Fill the Jar Halfway with Colored Water

A jar with red water and two straws coming out, part of a model heart project for kids.

Fill the glass jar half full of water. Add a few drops of red food coloring, creating the “blood” that will be pumped through your model heart.

Step 3: Cut Balloon

Cut the top off a balloon, leaving the bottom large enough to stretch over the mouth of the jar.

A white balloon with the top cut off ready to use in a model heart project.

Step 4: Place Balloon Over Jar

A white balloon being placed over the top of a jar.

Stretch the cut balloon over the top of the glass jar.

Step 5: Secure Balloon with Rubber Band

Use a rubber band to secure the balloon tightly in place so it doesn’t come loose.

A rubber band being secured over the top of a jar with a white balloon covering it.

Step 6: Add Tape

Putting tape on the top of a jar that will be used in a STEM project for kids.

Place a small piece of tape on top of each side of the stretched balloon. This helps to reinforce it where you’ll be poking the holes.

Step 7: Create a Small Hole in Balloon

Using a push pin, carefully poke a hole through the tape on either side of the balloon. The tape helps prevent the holes from tearing as you work.

Poking a small hole in the top of a a jar covered with a balloon preparing this STEM model heart project for kids.

Step 8: Tape End of Straw

Taping the end of a straw while working on this STEM model heart project for kids.

Take one straw and seal one end closed with tape. This straw will simulate the heart’s valve.

Step 9: Create an Extended Straw

Create a longer straw by cutting one straw in half and connecting it to another full-length straw, taping it onto the short portion just above the bendy joint. This will act as the main artery for your heart.

Creating an extra long straw while working on this STEM model heart project for kids.

Step 10: Place the Straws

Poking straws into the top of a jar while working on this STEM model heart project for kids.

Insert the sealed straw into one hole on the balloon, with the open end pointing downward into the liquid.

Insert the extended straw into the other hole, ensuring its end is in the red liquid.

Step 11: Seal the Gaps

Seal all gaps around the straws with tape to make the system airtight, which is crucial for the pumping action to work.

Sealing the gaps around the straws while working on this STEM model heart project for kids.

Step 12: Cut Hole in Water Bottle Cap

A small plastic water bottle with a hole in the top and a glass jar covered with a white balloon and straws coming out for this STEM model heart project for kids.

Cut a hole in the lid of the plastic water bottle, just large enough for the extended straw to fit through.

Step 13: Connect the Bottle

Connect the plastic water bottle to the extended straw by inserting the other end of the straw through the hole in the bottle cap.

Putting a straw into a hole on the top of a plastic bottle while working on this STEM model heart project for kids.

Step 14: Make the Heart Pump

Demonstrating the pumping of a heart by pushing two fingers down on top of a sealed jar that has red water in it. The water is then transferred into another bottle through a straw.

Now it’s time to simulate a heartbeat! Place two fingers on the stretched balloon and press down gently. This action will push the water up the sealed straw and through the extended straw into the plastic water bottle, mimicking how the heart pumps blood through the body.

Bonus Step: Decorate Your Heart Model

Take your heart model to the next level by adding decorations to your plastic water bottle. You can glue on small skeleton arms and a head to create a spooky look, perfect for an anatomical project or Halloween activity. Get creative with stickers, markers, or additional craft supplies to personalize your model.

A completed STEM project. A model heart pump made from two jars, colored water a cut balloon and straws.

The Educational Twist:

This activity provides a fantastic opportunity to discuss the science of the circulatory system. Talk about how the heart’s chambers work together to pump blood and how the arteries and veins transport it throughout the body. You can also explore why the heart is such a vital organ and how it supports life.

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