I like any activity in which the students experience the subject matter rather than just observe it or hear about it. In this activity, students observe changes to their respiration rates following exercise.
I have done this activity on a day when parents are visiting and available to help monitor respiration rates. Because respiration is both voluntary and involuntary, it can be difficult for students to monitor it themselves without altering their breathing. You may choose to have students work with partners to count their respiration rates.
One great thing about this activity is that if you have a clock with a second hand, you have all the materials you need.
I have included a rubric. I do not have specific answers I am looking for. Rather, I would like to see detailed observations, written in full sentences. I do expect students to edit their responses to reflect our class discussions. If student observations are anomalous, I do like to see them discuss the classes findings as well as their own.
This is a great companion to the Pulse Rate Lab, listed separately.