I don't know how to demonstrate the effects of of exercise and
rest on pulse rates
You could use the experiment where you count your average breaths in a minute 3 times and get the average. Then exercise for 2 minutes and count how many breaths you take. Next record how long it takes the breathing to return to normal. Compare the rate of breathing at rest with the rate after exercise.
im doing it the same way but instead of breathing you use your pulse