# 25. GASP!

SUBJECT: Science
GROUP SIZE: Small
TIME: 60 minutes
TYPE OF ACTIVITY: Student Investigation
TEACHING STRATEGY: Guided Discovery Expository
CONCEPTS: Anoxia Closed Environment Rate of Use
SKILLS: Experimentation Collecting and Interpreting Data

Objectives: To measure the rate at which oxygen is used in a closed environment; to understand the importance of knowing the rate at which oxygen is used in a closed environment.

Materials: 250ml flask or bottle; pipe cleaners; glass tube; ink; 1 one – hole rubber stopper to fit the flask; calcium hydroxide (lime water); small animal(s)-mouse or crickets or cockroaches, etc. (The smaller the organism, the slower the movement of the ink.)
Procedure:

Place a small animal(s) into the bottle along with a pipe cleaner soaked in calcium hydroxide. Stopper the bottle with the stopper containing a short glass tube. It is important to seal the bottle well or air leaking in may spoil the experiment.

DO NOT PLACE THE GLASS TUBE IN THE STOPPER WITH YOUR BARE HANDS. PLACE GLYCERIN ON THE TUBE FIRST TO ALLOW IT TO SLIDE INTO THE STOPPER MORE EASILY. WRAP THE TUBE WITH A TOWEL IN CASE IT BREAKS WHEN INSERTING IT.

Place a small drop of ink on the open end of the tube outside the bottle. Wipe off the excess. Observe the movement of the ink marker inside the tube. Calibrate the tube every minute until it enters the bottle. Use different numbers of animals in the flask or try different kinds of organisms. Calibrate the tube for each kind of organism. Can your students predict what the rate will be when several organisms are placed in the flask based on their data for a few or one? Why would it be important to know the rate at which an animal uses oxygen? Relate this to people on board a space craft.
Extensions: (1) Have the students explore the symptoms of anoxia (lack of oxygen) in humans. Think of ways to create oxygen on board a space craft.

(2) Have the students do Activity #84 – “Oxygen Production” in the K – 6 COME FLY WITH ME materials before they do this activity if you feel they need more background.

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