Respiratory System

The following activity can be used to enhance instruction of the respiratory system.  This activity is also found under acid/base balance.

· Many students do not understand the chemistry involved in acid/base balance – buffering systems.  Here’s a fun way to help them understand.  I call it Buffer Ball:

Get yourself 3 nerf balls (or other soft balls) of different colors.  Designate the projectiles as H+, ‘combine,’ and ‘dissolve.’  Write on them if possible.
Then have the students make themselves signs that include name and formula for other players in the buffer system : carbonic acid, bicarbonate, carbon dioxide and water.
Designate an area of play.
Have some of the participants sit on the sidelines with a stack of signs so they can adopt molecular status as needed.
Toss the balls to the players in the area of play.
Whoever catches a ball should react appropriately depending on the label of the ball.  If they catch and react with an H+, then they should step to the sidelines and exchange places with a student wearing the appropriate sign for what they have become.  The player who has just left the field of play then tosses the ball to someone else.
If a player catches the ‘combine’ or ‘dissolve’ ball and can do so, they should either find another player with whom they can combine and together go to the sidelines so that the new molecule can take their place – OR, in the case of dissolve, go to the sidelines and have 2 people take their place with appropriate signs.
If the caught ball has no effect on the catcher, he or she should toss it to someone else in the field of play.
There is room for a lot of variation and manipulation with this idea.  You can flood the system with CO2 as if the person has COPD and hoards CO2, or you could reduce the amount of CO2 present as if the person is hyperventilating.
You could establish the number of signs in a plausible ratio for a body with normal pH, or just play to give the students the idea of the chemistry involved and the constant shuffling that makes a buffer system work.

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