Name ________________________________________
Number _______
Period _____
The Scientific Method – An Introduction
Introduction:
In this lab you will learn to form a hypothesis, conduct experiments around that hypothesis, and collect
and analyze data. One of the most important characteristics of modern science is its quantitative
approach to solving problems. One of the first scientists to use quantitative methods was William
Harvey, who discovered that blood circulated through the body. At the time Harvey began his work,
anatomists believed that the liver produced blood from the food that the body consumed. The blood was
then carried by veins to the heart, purified in the lungs, and then pumped to the various organs of the
body, where it was consumed. Harvey measured that the left ventricle of the heart held roughly 100 ml
of blood. He also measured that the heart beats an average of 64 times per minute.
Materials:
Watch with second hand, or clock
Procedure:
Part 1:
1. While sitting quietly at your desk, find the pulse in your wrist and count the beats for one minute.
You and your lab partner can do this on yourselves, or each other. Record your name and beats
per minute in DATA TABLE 1 as sample 1.
2. Repeat step 1 two more times. Record the data in the appropriate place on DATA TABLE 1.
3. Calculate your average pulse rate and record the results on DATA TABLE 1.
DATA TABLE 1: Resting Heart rate
NUMBER OF BEATS PER MINUTE
Name
sample 1
sample 2
sample 3
AVERAGE NUMBER OF
BEATS PER MINUTE
(add 3 samples then divide by 3)
Your Name
Your Partner’s Name
Part 2:
How do you think standing breath will affect your pulse rate?
1. Formulate a hypothesis about the effect of standing on pulse rate. List the independent and
dependent variables.
Heart Rate Standing:
Hypothesis _________________________________________________________________
Independent Variable _______________________________________
Dependent Variable ________________________________________
2. Repeat steps 1, 2, and 3 from PART 1, this time standing. Record your data and calculations in
DATA TABLE 2.
DATA TABLE 2: Heart rate standing
NUMBER OF BEATS PER MINUTE
Name
Your Name
Your Partner’s Name
sample 1
sample 2
sample 3
AVERAGE NUMBER OF
BEATS PER MINUTE
(add 3 samples then divide by 3)
Part 3:
How do you think holding your breath will affect your pulse rate?
1. Formulate a hypothesis about the effect of holding your breath on pulse rate. List the
independent and dependent variables.
Heart Rate While Holding Your Breath:
Hypothesis _________________________________________________________________
Independent Variable _______________________________________
Dependent Variable ________________________________________
2. Repeat steps 1, 2, and 3 from PART 1, this time holding your breath (NOTE: You will be sitting
while doing this – remember, it’s a controlled experiment). Record your data and calculations in
the DATA TABLE 3.
DATA TABLE 3: Heart rate holding breath
NUMBER OF BEATS PER MINUTE
Name
sample 1
sample 2
sample 3
AVERAGE NUMBER OF
BEATS PER MINUTE
(add 3 samples then divide by 3)
Your Name
Your Partner’s Name
Conclusion: Compare your data.
1. How do your results in Parts 2 & 3 (standing and holding your breath) compare with the
hypothesis you made for each condition?
Standing:
___________________________________________________________________________________________
___________________________________________________________________________________________
Holding Breath:
___________________________________________________________________________________________
___________________________________________________________________________________________
2. What is the control group in this investigation?
_________________________________________________________________________
3. What are some possible sources of error in this experiment (why might your results be biased or not quite
right)?
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
4. Create a bar graph (on a sheet of graph paper) that shows the average beats per minute for your
heart rate and your partner’s while resting, standing, and holding your breath. Make sure you
label each axis, give your graph a title, and label each bar. REMEMBER: Graphs should be as large
as possible – use all the available space!