1. The skipping and jumping jacks raised my heart rate the most. They were putting the most stress on my heart, so it started to pump very fast to get enough oxygen to my muscles.
2. Sitting and standing increased my heart rate the least. I didn't need as much oxygen because my muscles weren't working hard.
3. I was accurate when I ranked the activities. My heart rate number got bigger when I did the next activity.
4. My heart rate got a lot faster when I was more active. I needed to get a lot more blood and oxygen to my body, so my heart needed to pump more of it faster.
5. I think that because I was straining my muscles more, they needed more oxygen. Our blood carries around oxygen, so the heart needed to pump out more blood.