The Amazing Heart
Topic: The heart and blood flow through the heart will be discussed and blood
throughput will be calculated.
Description: First the students will find how exercise affects their heart rate. They will
also calculate the amount of blood a ‘famous’ athlete’s heart can pump in a given time
interval.
Anticipatory Set: Have pictures of athletes on a slide show along with questions such as
“how much blood does Darren McFadden’s heart pump in one hour?”
State Standards:
 Explain the functions of the heart and lungs (lungs were discussed in a
previous lesson)
 Describe and illustrate blood flow.
Materials:
 Paper towel roll (1 for each 2 students)
 Stop watch
 Handouts
 Mini marshmallows
 Toothpicks
 Cardiac output for a few athletes.
o The cardiac output can be found by finding the surface area of the
individual and multiplying it by the cardiac index (the cardiac index for
children is about 2.75 L/m2 per minute, the estimated cardiac index for an
adult is 3.5 L/m2 per minute). The surface area can be found by using a
nomogram (in background section). Using a ruler to connect the weight of
the person with the height of the individual, the place where the ruler
crosses the center line is the surface area for the person in question.
Prerequisite Skills: The students should have some basic idea of how the heart and
lungs work and the blood flow in through the two organs. This was discussed in previous
lessons but refreshed before starting the lesson.
Management: The students worked together in groups of 4 making it easier to get
organized with a buddy.
Procedure:
The Beat Goes On: The students usually find it hard to find their pulse by placing their
fingers across their wrists, so instead we used paper towel rolls as a stethoscope.
Working in pairs of two, the students found their resting heart rates. After jogging in
place for a minute, the students found their active heart rate. The students compared their
heart rates to that of their group members.
In a Heartbeat: The students found their heartbeat by watching a ‘beat measuring
device.’ This device was made by sticking a toothpick into a mini marshmallow and
placing it on the pressure point on the students’ wrist. When the ‘device’ was placed in
the correct place, the toothpick will clearly move side to side along with the heartbeat.
This activity was only tried with one class due to time constrictions. The students had a
hard time finding the pressure spot on their wrists.
Keep On Pumping: In order to show the students just how amazing the heart really is in
terms of amount of blood pumped, the students calculated the cardiac output (amount of
blood pumped in one minute). To avoid any issues or complaints we found the cardiac
output of well known athletes instead of the cardiac output of the students themselves.
Each group was given an athlete and to make it more fun, the information can be given
on stat card, giving a bit of info about the person along with the information needed to
calculate the cardiac output. Since we were pressed for time, instead of having the
students find the surface area of their athlete, it was given to them. Using that, they
multiplied it by the cardiac index to find the cardiac output. The cardiac output was used
to calculate the amount of blood pumped in different time intervals, and the amount of
blood was compared to a known volume such as a 2L coke bottle or gallon of milk. The
stroke volume (amount of blood pumped per beat) was calculated by dividing the cardiac
output by the average heartbeat per minute. Since these are athletes the average heartbeat
per minute will be a bit different as well as the cardiac index, but it gets the point across.
Since we just did conversions in math, a few conversions were thrown in to at the end.
Cardiac Output:
(Assuming cardiac index of 3.5 l/min/m2)
Darren McFadden: Arkansas Razorback Football
Ronnie Brewer: Arkansas Razorback Basketball
Matt Jones: Jacksonville Jaguars (NFL) former Razorback
Joe Thornton: San Jose Sharks (NHL)
Amanda Beard: Olympic Swimmer
Mia Hamm: Olympic Soccer Player
Name
Darren McFadden
Ronnie Brewer
Matt Jones
Joe Thornton
Amanda Beard
Mia Hamm
Height
6’2
6’7
6’6
6’4
5’8
5’5
Weight
205 lbs
217
238
235
128
125
Surface Area
2.2 m2
2.36 m2
2.41 m2
2.38 m2
1.67 m2
1.6 m2
Cardiac Output
7.7 l/min
8.2 l/min
8.4 l/min
8.3 l/min
5.8 l/min
5.6 l/min
Discussion and Follow-Up Activities: The students discussed reasons why their heart
rates would differ as well as why thy cardiac output would be different for the different
athletes. We also did some conversions for volumes since we discussed that in math just
a couple weeks before.
We discussed the heart beat of different animals and how their size and heart rates
compared. The average age and number of heart beats per minute was also discussed.
Example: A mouse's heart beats about 700 times per minute and an elephant's about 30.
A mouse lives less than three years, an elephant more than 60, do you think there is a
connection? What is it?
Reflection: Over all the activities went well. The students enjoyed listening to each
others heartbeats and liked getting up out of their seats and doing something (running for
a minute). They also enjoyed calculating the cardiac output for people they admire such
as the local football and basketball heroes.
The “In a Heartbeat” activity was cut short because of time and because the students had
difficulty finding the right spot to place their ‘heartbeat device.’