If you're looking for a cool, inexpensive science fair project, try making a working model of the human heart. By using some common household items and two balloons, you can easily complete this project in an hour or so. This project is sure to impress your teachers and classmates.
Take two balloons and stuff one inside the other to make a double layered balloon. Repeat this process to make two double-layered balloons.
Replace the rubber bladders on each of the turkey basters with the double-layered balloons. Cut the plastic tubing in half to make two 5-foot lengths.
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Place a single balloon on one end of each length plastic tubing and secure them with rubber bands. Secure both tubes to each other to keep them from moving.
Inflate the double-layered balloons about three-quarters full by blowing into the narrow end of the turkey basters. Pinch off the end of the balloons to keep them from deflating while you fit the narrow ends of the basters into the open ends of the plastic tubing. They should fit very snugly and form a tight seal. Allow the air to move through the tubes into the single balloons on the other end. Squeeze both double-layered balloons and watch the single balloons pulsate.
Glue the single balloons together; these are going to be your main chambers. Mix some of the liquid latex with red food coloring and paint some of this mixture onto the balloons. Cover the chambers with a layer of toilet paper and repeat this process until the two balloons resemble a human heart. Keep a picture of a human heart with you for reference. If necessary, you can glue another balloon to the model to fill out more space and make it look more realistic. Cover this balloon with layers of liquid latex and toilet paper. When you're satisfied with the shape of your heart, paint on a layer of fake blood to make the color more realistic.
Set up your heart model on a disposable baking sheet and use the double-layered balloons to make it pump during your demonstration.