How to make a lung model

This activity is part of our Science Lab series. Check out the ANU Science Lab for more experiments! In this activity, you will construct two different lung models using everyday materials to learn how to make a model of the lungs and explore how lungs work, explained in a fun, visual way. Watch the video above to see how it's done.

Materials Needed 

• Picture of lungs printed on paper 
• A small cardboard box 
• Plastic water bottle 
• 3 balloons Y-connector (three-way plastic connector) 
• Flexible vinyl tubing or plastic pipe 
• Syringe 
• Small rubber bands or hair ties 
• Scissors 
• Blue tack 
• Tape 
• Superglue

Safety Note: Take care when cutting plastic bottles and poking holes through plastic caps with scissors.

Instructions Model 1: The Interactive Lung Box

1. Prepare the Box: Glue the picture of the lungs onto the front of your cardboard box, and secure the box lid in place so the box stays shut.
2. Assemble the Lung Branch: Attach one balloon onto each of the bottom two prongs of your Y-connector. Pinch the neck of each balloon slightly over itself to create a tight seal, then wrap tape securely around the connection points.
3. Attach the Airway Tube: Insert your plastic pipe or vinyl tube into the top stem of the Y-connector and seal the joint tightly using blue tack.
4. Mount the Structure: Carefully use scissors to pierce a hole in the top of your cardboard box. Apply glue to the back of the Y-connector and stick it onto the lung picture on your box. Thread the tubing out through the hole in the top of the box.
5. Connect the Syringe: Fill your syringe with a bit of air and insert the nozzle into the exposed top end of the tubing. Push and pull the syringe plunger to watch your balloon lungs inflate and deflate.

Model 2: The Diaphragm Chest Cavity 

1. Cut the Bottle Cavity: Carefully cut off the bottom third of your plastic water bottle using scissors, then set the bottom part in recycling. The remaining top section of the bottle acts as your chest wall and rib cage.
2. Make the Diaphragm: Take one balloon and cut off the narrow neck. Stretch the wide body of the balloon tightly across the open bottom of your cut bottle, then wrap tape around the edge to lock it in place.
3. Prepare the Bottle Cap: Unscrew the bottle cap, place it flat on a table, and carefully use scissors to make a hole through the center. Thread your piece of plastic tubing straight through the cap.
4. Attach the Interior Lung: Slip a full balloon over the bottom end of the tubing (the end that will sit inside the bottle). Wrap small rubber bands or hair ties tightly around the balloon neck to clamp it onto the tube securely.
5. Final Assembly: Thread the balloon lung down inside the bottle cavity and screw the cap back onto the bottle tightly. Seal around the hole in the cap with blue tack if needed to keep the chamber airtight.
6. Test Your Diaphragm: Pull down on the stretched balloon at the bottom of the bottle to watch the internal balloon expand with air, then release it to watch it deflate.

Why It Works 

Breathing relies on changes in air pressure created inside your chest cavity. The first model shows the intuitive view of respiration: when you inhale, air travels down your trachea (windpipe) to fill your left and right lungs, expanding them like balloons.

The bottle model demonstrates the actual mechanical process driven by physics (specifically Boyle's Law):

• When you inhale, your brain tells your diaphragm (the dome-shaped muscle beneath your lungs) to contract and pull downward.
• Pulling the diaphragm down increases the overall volume inside your chest cavity, which drops the air pressure inside below the outside air pressure.
• Air naturally flows from areas of high pressure to low pressure, so air from outside rushes down your windpipe to fill your lungs.
• When your diaphragm relaxes and moves back up, the volume decreases, pressure rises, and air is pushed back out as you exhale.

Science fair projects & taking it further: Experimenting with variables

• Pneumothorax simulation: Poke a tiny hole in the plastic bottle wall to simulate a punctured lung (pneumothorax). Observe how losing an airtight seal affects the diaphragm's ability to inflate the balloon!
• Exercise & breathing rate: Measure your breathing rate before and after doing 30 jumping jacks. How does physical activity alter how quickly your diaphragm contracts?

Enjoyed this experiment? Explore more hands-on activities on the Science Lab ANU YouTube channel.