Sitting quietly at your desk, watching TV, or lying in bed at night, your heart should be taking it easy – beating steadily and calmly at somewhere between 60 and 80 beats per minute for most healthy ...

Note: This video is designed to help the teacher better understand the lesson and is NOT intended to be shown to students. It includes observations and conclusions that students are meant to make on ...

Note: This video is designed to help the teacher better understand the lesson and is NOT intended to be shown to students. It includes observations and conclusions that students are meant to make on ...