Independent variable: time of exercise, or even type of exercise
Dependent variable: breathing rate, breaths per minute
- Student A breathes as normally as possible, with an indication of when they breathe in and out
- Student B records the breathing rate of student A in breaths per minute before the exercise
- Student A runs one lap of a playing field (or another exercise)
- Student B records the total number of breaths taken in each minute after the exercise. Steps 2-4 are repeated 3 times for accuracy, though as the student A begins to feel tired, the accuracy may drop as the heart rate would already have been accelerated by the previous exercise. Although you cannot introduce a new student C, validity, you can repeat this experiment the next day when student A is well rested.
- Rate of breathing is plotted on a graph, breathing rate on the y axis and the time/type of exercise on the x axis.