Hands on learning is the way to go in a science classroom-this has always been my saying. I cannot emphasize this enough-I think every science and health unit should have at least one hands on activity a week. When it comes time to studying the human respiratory system-making plastic bottle lung models is something you may want to consider adding to your lesson plans. It is an easy activity that can be completed in a class period’s worth of time. I think it is especially a hit with middle school aged students. This model will help students gain a better understanding of the role the diaphragm muscle plays in the process of inhalation and exhalation.
Materials
-Plastic bottle with label removed (like a water or soda bottle, 16 fluid ounce or larger)
-Plastic kitchen size trash bags
-Balloon
-Strong adhesive tape
Preparing for the Activity
1. Tell your students in advance to bring in a used, washed, and thoroughly dried (no water drops in it) plastic water or soda bottles. Have them remove the paper label off the bottle. They can tape a small piece of paper with their name and period on it to their bottle.
2. Make sure students bring in bottles that are NOT too thick (like Gatorade sports drink bottles or Vitamin water). This will make for dangerous cutting! The regular water bottles and some soda bottles that are squeezable plastic are much easier and safer for cutting out the bottom half.
3. Size-wise, you may use 16 FL ounce or larger (yes, the large soda bottles work, too). If the bottle is too small there won’t not much room inside for the lung balloon to expand. In my experience, these did not make the best lung models, so I prefer to use a larger sized bottle.
*As for the plastic bag-use the small bathroom trash can bags ones that come in a roll. Roll out the plastic trash bag and if you want to save time in class, you can tear out enough squares ahead of time for each student. How big of plastic bag squares cut outs will depend on the size of plastic bottle chosen for the project. Basically, you want a square that is large enough to cover the cut side of the bottle and still have enough bag left to be able to make a twisted handle out of as you see in the picture below. Once you tear out a bag, it should not need to be cut with scissors, it will just need to be adjusted to fit the bottle the way you like it. Now, let's get started!
Step 1
Take a balloon and place the open side around the mouth of the bottle as shown in the picture below. The balloon will be sit inside the bottle.
Step 2
Now, using scissors, carefully cut a slit in the side of the bottle (see picture), Then from there continue cutting around the bottle. Now you have bottle with an open side.
Step 3
Now it’s time to close, or cover, the bottom half of the bottle with the plastic trash bag that was pre-cut. This is the tricky part. Before you tape the square cut out on to the bottle- first, place the bag over the cut part of the bottle and adjust it so that you have enough slack to make a handle out of it (the longer the handle the better). Place the bag at least 1 inch below the balloon, so that the bag will not cover the balloon once it is taped on. See the picture below.
Step 4
Once you have the bottom the way you want it, then you will need to securely tape it to the bottom of the bottle making sure NOT to leave any holes or gaps in it. The bottle must be sealed completely, so that no air can escape. If any air gets in (even a little air), the lung balloon will not expand fully. For this step, it helps to have someone else hold the bag in place on the bottle while another person tapes it- this ensures it will be sealed the way you want it. After you tape the bag on to the bottle you will have a long "tail". I like to use the tape shown below; It is stronger than regular tape.
Step 5
Now, what to do with this long tail? First, lie the bottle down on a flat surface and tape any openings in the bag. See the picture below.
Step 6
Next, twist the "tail" tightly together at the end to make a handle that will act as the diaphragm in the model. Then tape the tail together, tie a knot in it, or twist tie it. However you make the diaphragm handle- be sure that no air escapes from the model. Make it air tight-TAPE IT WELL, or the balloon will not inflate as much as it should. Notice the knot in the picture below.
This is the handle that will represent the action of the diaphragm muscle. When you pull down on the handle, the balloon will expand as it fills with air (representing the lungs during inhalation) and when you push upward on the handle, air will be forced out of the balloon (representing the lungs during exhalation). The bottle itself represents the chest cavity. This model will demonstrate the action of one lung in the body, but if you prefer to have your students make a two-lung model, then check out this web page: two-lung bottle lung model. It just might take a little longer to do in class than the simple, one-lung model demonstration.
Additional Experimentation
You can have your students place some water in the balloon after they have made the model and then test how well the balloon will fill with air when they use the handle to make the diaphragm move downward. Tell them that fluid in the lungs can be caused by many conditions, one being a lung infection, like pneumonia. By adding water to the balloon, they can see how fluid in the lungs affects a person's breathing.
Good Stuff- Why not?
Click here for The Biology Buzz Place Plastic Bottle Lung Model Questions Worksheet. It is a FREE resource offered in my store. So, once your students make their models, they can then complete this worksheet and turn it in to you.
The Biology Buzz Place Respiratory System Presentation pairs well with this activity. It provides the informative material students’ needs to know on how the human respiratory system works.
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