Your heart rate can be determined by counting the number of times your heart beats per minute. There are several places you can find your pulse—the rhythmic pressure wave of blood in the arteries. The radial pulse can be found by placing two fingers just below the wrist creases at the base of the thumb. Another common place to feel the pulse is the carotid artery in the neck. Place two fingers, index and middle, between the trachea and large neck muscle. Be sure to sit still without talking, and slowly move the fingers together until you can feel the blood flow. In this experiment, you’re collecting data to determine how holding your breath affects your heart rate. Write a hypothesis stating whether your heart rate will increase, decrease, or stay the same after holding your breath for 30 seconds. Also, identify the independent and dependent variables. Hypothesis: Independent variable: Dependent variable: