Blood and Guts – The Lungs

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I decided to make one gigantic post for this one (well, all but the dissection – which is next week!).

I always love, love, love lab day in science.  I really wish we had two hours to do what we need to, but we only have our 45-minute allotment.  Because of the time restriction, we have to h-u-s-t-l-e when we build models and/or do experiments.  It requires the kids to stay focused and act quickly.  Sometimes that can be a little hard, especially if there’s a lot to cover.  Today was one of those days: a lot to cover, and not a lot of time.  The kids (as usual) did wonderfully.

We’re on Lesson 6 (respiratory system) now, because we skipped Lesson 5 (nutrition).  If we have enough time at the end of the year, we’re add that to the end.  Yes, it’s important, but I felt it was more necessary to cover the parts first.

For today’s lab on the lungs, we built two models and did one (very) quick experiment.  In the first model, we built lungs, and in the second model, we showed how the diaphragm is responsible for inflating and deflating the lungs by pulling and pushing them.

Here’s how we built the lungs:

We started out with two candy bags.  You can find these at Walmart or at a craft store where the cake decorating/candy making stuff is.

We started out with two candy bags. You can find these at Walmart or at a craft store where the cake decorating/candy making stuff is.

 

Next, using Sharpies, we drew a whole lung on one bag and the bronchus and alveoli on the other.

Next, using Sharpies, we drew a whole lung on one bag and the bronchus and alveoli on the other.

 

Then we outlined them in black.

Then we outlined them in black.

 

We placed a straw in each bag.

We placed a straw in each bag.

 

Finally, we gathered the tops and tightly taped them around the straws.  We also taped the two straws together to represent the bronchial tubes.

Finally, we gathered the tops of the bags and tightly taped them around the straws. We also taped the two straws together to represent the bronchial tubes.

 

Some fun shots of the kids having a great time inhaling and exhaling to make the bags inflate and deflate:

With our second model, I had the kids pair up.  It was a good exercise in having a “lab partner.”  I found the instructions for this here.  Here are the finished products:

 

And finally, the experiment.  The kids each had a clear cup and were instructed to fill it halfway.  I gave them each a straw, and went to each cup, adding a few drops of Bromothymol Blue, which turned the water a nice, deep, blue color.  They took the straw and gently blew into the water.  They discovered that as they exhale, they breathe out a weak acid, called carbonic acid.  Because Bromothymol Blue is the active ingredient in liquid PH-testing solution, their breath turned the water yellow.  It took about 2-4 minutes for it to happen, but when it did, there were a whole lot of ooh’s and ahh’s.

You can find Bromothymol Blue in pet stores that carry a lot of choices for aquariums.  Most places only sell the PH-testing strips, but you need the solution.

Here are the kids finishing up the experiment:

Next week’s lab:  dissection!  Yay!

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2 responses »

  1. Hi! I have enjoyed looking at your blog today! I wish I had found it earlier. Do you have tests for the other lessons? We are on chapter 9.

    • I actually administered tests for the first couple of chapters because I realized early on that some kids do well on tests, and others don’t. I basically decided to do an on-going test in class as we studied the book. That worked fabulously!

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