Activity: Does caffeine increase heart rate?
This Activity is designed to be a finale for Chapter 4, and will allow students to think and reason about all of the learning targets in the Chapter.
Prepare your treatments ahead of time. Pour small cups of soda, half of which are labeled A and contain regular Coke and half of which are labeled B and contain caffeine free coke (or the other way around). Dixie 3-ounce cups work well.
This Activity is designed so that students can work through the questions without direct instruction from the teacher (typical). But we do suggest that you are the one facilitating the experiment. Have all students take their starting pulse at the same time. Have all students take their treatment at the same time. Have all student take their ending pulse at the same time.
When we did this Activity, there was very little difference in the mean change of pulse rates between the two groups (the mean change in pulse rate was actually lower for the caffeine group). This is not very exciting. It has been suggested (by an author who I won’t name) that you manipulate the data a bit to make this more exciting. You can do this by having students measure their pulse rate for 30 seconds and then double the count. For the initial heart rate, you might call time a bit early (like at 28 seconds) and for the final heart rate you might call time a bit later (32 seconds). It is OK to lie to students if it is in the interest of better statistics instruction.
Chapter 4 Big Ideas
There is so much vocabulary in this Chapter. We also used this chart of Chapter 4 Big Ideas to help students review.