That is the tidal volume. To get a measure of the vital capacity, repeat the activity with the students exhaling a deep breath into the hose. To set-up easily for the next student, use a funnel to carefully pour water from the tub back into the emptied 2 liter bottle. There are three different measurements of lung capacity that can be done. Vital capacity is the largest amount of air that can be exhaled after taking a deep breath.
Tidal volume is the amount of air taken in during normal breathing.
Expiratory reserve is the air that is left in the lungs after exhaling in normal breathing. A well-trained athlete has a greater lung capacity. Language Arts Connection Have students work in groups in order to discuss and write a comparison on the two different methods of lung capacity measurement. This method is neat and inexpensive, but probably not as accurate as the others. You must decide which of the methods you prefer before starting the lesson.