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4. Percents
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United States of America
Grade 7

Investigation: Heart rate

Lesson
Practice
Overview
Activity
Reflection

Investigate your heart rate and consider how often your heart beats over different increments of time.

Objectives
  • To investigate rates in real life.
  • To see the importance of understanding rates.
  • To explore percent change.
  • To practice with direct proportion in real life.
Materials

Heart rates

Procedure
  • Sit in a relaxed position without crossing any of your limbs.
  • Take your pulse for 20 seconds. To do this you can place your middle and pointer fingers firmly on your neck, wrist, or the inside of your elbow.
  • Record the pulse you counted when the time is up.
Fill in the provided table based on your recorded heart rate. Then, graph the results in the provided cartesian plane.

Article that discusses various factors that can influence heart rate.

Factors that can influence heart rate
Investigate
Consider the following questions once you have recorded your heart rate.
1.
If your heart continued at this rate, how many times would your heart beat per minute?
2.
If your heart continued at this rate, how many times would your heart beat per hour?
3.
If your heart continued at this rate, how many times would your heart beat per week?
4.
Using the provided link, look up factors that may influence the amount of times a person’s heart beats per minute. Based on this do you think your weekly estimate is too high or too low? Why?
5.
What would be a more accurate prediction as to how many times your heart beats a week?

Discuss your responses to the previous questions with a classmate, then answer the questions below.

Discussion
1.
Was their heart beat per minute greater or lower than yours?
2.
What was their weekly estimate for the amount of times their heart will beat? Compare and contrast how you arrived at your estimates.
3.
The average person will have a resting heart rate between 60 and 100 beats per minute. Some people have heart rates that are over 100 beats per minute. These people have a condition known as Tachycardia. If you were a doctor and had a patient who had a resting heart rate of 9000 beats per hour would you diagnose them with Tachycardia? Why or why not?
4.
If someone with a resting heart rate of 9000 beats per hour was diagnosed as Tachycardiac, by what percent does their heart rate differ from the average resting heart rate of a generally healthy person (80 beats per minute)?
5.
Take the average of you and your partner’s heart beats per minute. By what percent does your collective average heart rate differ from the average resting heart rate of a generally healthy person (80 beats per minute)?
6.
Is there a way that you could increase this percent difference from your findings? How?
7.
If your resting heart rate increased by 10\% would you still be considered generally healthy? Explain.

Outcomes

7.RP.A.1

Compute unit rates associated with ratios of fractions, including ratios of lengths, areas and other quantities measured in like or different units.

7.RP.A.3

Use proportional relationships to solve multistep ratio and percent problems.

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