Scientific Method
Background: The Scientific Method is what we use in class to solve problems/answer questions based on
the experiments we do in class. All of the experiments will include certain parts that will be reviewed
below.
Section 1:
INDEPENDENT VARIABLE or MANIPULATED VARIABLE – the ONE kind of thing that I change in an
experiment. You choose to change this thing. A lot of the time, you will have a list of things that will go
in this category.
EXAMPLE #1: The types of music. My list of things would be music like Rap, R&B, and Hip-Hop
EXAMPLE #2: The types of liquid. My list of things would be water, milk, lemon juice, and soda
DEPENDENT VARIABLE or RESPONDING VARIABLE – what is being measured/recorded in the
experiment. This is the kind of answer you’re trying to get for your question.
EXAMPLE #1: the fastest average heart rate
EXAMPLE #2: the time for an apple slice to turn brown
CONSTANTS – all of the things you keep the same when you do the procedure to make each trial fair.
The ONLY thing YOU should change (or is different) when you do the experiment is the INDEPENDENT
VARIABLE. EVERYTHING ELSE HAS TO BE DONE THE SAME WAY!!!
EXAMPLE #1: Listen to each type of music for 3 minutes, sit in the same chair in the same room
when listening to the music, listen to each type of music at a volume of 4
EXAMPLE #2: Use a Macintosh apple slice for each liquid, use the same thickness of apple slice,
use 10mL of each type of liquid
CONTROL – shows us what happens normally. It’s the thing without the independent variable!
EXAMPLE #1: Sitting in the same chair in the same room for 3 minutes without listening to music
EXAMPLE #2: Testing how long it takes for the apple to turn brown with no liquid on it
NOT ALL EXPERIMENTS HAVE CONTROLS!!
Section 2:
IDENTIFYING A TESTABLE QUESTION: We need to have a question that can be answered by
testing out or “doing” an experiment. The testable question is what we are trying to figure out by doing
the experiment.
Here are a couple formats for writing the TESTABLE QUESTION:
What is the effect of THE INDEPENDENT VARIABLE on THE DEPENDENT VARIABLE?
Which INDEPENDENT VARIABLE will DEPENDENT VARIABLE?
How does THE INDEPENDENT VARIABLE affect THE DEPENDENT VARIABLE?
EXAMPLE #1: What is the effect of the types of music (rap, r&b, and hip-hop) on the fastest
average heart rate?
EXAMPLE #2: Which type of liquid (water, milk, lemon juice, and soda) will keep the apple slice
from turning brown the longest?
Section 3:
WRITING A HYPOTHESIS: We need to make a GUESS that will answer our testable question.
The format for writing the HYPOTHESIS is:
If I test THE INDEPENDENT VARIABLE to determine THE DEPENDENT VARIABLE then the
CHOOSE AN ITEM FROM YOUR INDEPENDENT VARIABLE LIST will have THE DEPENDENT
VARIABLE because EXPLAIN YOUR REASONING.
EXAMPLE #1: If I test the types of music (rap, r&b, and hip-hop) to determine the fastest
average heart rate then hip-hop will have the fastest average heart rate because it has a faster beat so
it will make my heart beat faster.
EXAMPLE #2: If I test the types of liquid (water, milk, lemon juice, and soda) to determine the
time for the apple slice to turn brown then lemon juice will keep the apple slice from turning brown the
longest because lemon juice is closest to being apple juice which is naturally in the apple slices.
Section 4:
EXPERIMENTAL DESIGN: This tells how we are going to perform our experiment and what supplies we
are going to need.
1.
Include a MATERIALS LIST of what you need to do the experiment. It may be helpful to fill
this in after you write out the procedure. Reread your steps and write down the materials you
used.
2. Procedure should be specific and should go in order. Be sure to number the steps!
3. It may be helpful to draw a picture of your design before you write the procedure. Use a few
words to show amounts, timing, etc.
4. Make sure you have written the amounts you are using and that they are the same for each thing
you are testing.
Section 5:
DATA TABLES: This table will organize the results of your experiment.
1.
Should have a title: The effect of THE INDEPENDENT VARIABLE on THE DEPENDENT
VARIABLE. You can always use your TESTABLE QUESTION as your title as well!
2. All columns should be labeled.
3. If you are recording numbers, there should be units after the numbers.
4. Most of the time you will have more than one trial or test done and will need to find the average!
EXAMPLE:
The effect of the types of music (rap, r&b, and hip-hop) on the fastest average heart rate
Type of Music
Heart Rate (bpm)
Trial 1
Trial 2
Trial 3
Average
56 bpm
62 bpm
60 bpm
59 bpm
R&B
54 bpm
54 bpm
54 bpm
54 bpm
Hip-Hop
62 bpm
64 bpm
63 bpm
63 bpm
Rap
Section 6:
CREATING A GRAPH: There are two types of graphs that you may make to display your data, a bar
graph or a line graph. If your independent variable is a list of things, such as types of music (rap, r&b,
and hip-hop), then you will make a bar graph. If your independent variable is a list of numbers, such as
the amount of time (5 mins, 10 mins, and 15 mins), then you will make a line graph. All graphs need to
have the following things:
1.
A SPECIFIC TITLE:
FORMAT: The effect of THE INDEPENDENT VARIABLE on THE DEPENDENT VARIABLE
2.
Y axis is labeled (the DEPENDENT VARIABLE)
3. Y axis has units
4. Numbers are written on a LINE NOT in the box
5. Y axis spacing is the same (each line goes up by the same amount)
6. X axis is labeled (the INDEPENDENT VARIABLE)
7. X axis spacing is the same (starting from the number line, each bar or dot is spread out by the
same amount) Each bar should also be the same thickness.
8. X axis has units if there are numbers on this axis
9. The “0” is at the corner
10. A ruler is used to make straight lines/bars because NEATNESS COUNTS!!!!
Section 7”
CONCLUSIONS: This part of the lab summarizes the results of the experiment and allows you to
address problems and improvements for future labs. There are two parts to a conclusion.
DATA ANALYSIS: In this part of the conclusion, you should restate your question and hypothesis,
describe if your hypothesis was supported or unsupported, provide data for the tests to support
you statement, and then answer your testable question.
EXAMPLE: This experiment tested how the types of music (Rap, R&B, and Hip-Hop) affect a
person’s heart rate. My hypothesis said that the Rap music would make the heart rate the fastest, but
it was unsupported. The Rap music only had an average heart rate of 59 bpm. The R&B music gave an
average of 54 bpm, and the Hip-Hop had an average of 63 bpm. Based on the experiment, the Hip-Hop
music would actually make a person’s heart rate the fastest.
SOURCES OF ERROR/IMPROVEMENTS: In this part of the conclusion, you should mention any errors
(at least 2) that may have affected your results or made them invalid. Make sure you mention
HOW they affected your results. Then, think of ways (at least two) to improve the experiment to
fix the experimental errors.
EXAMPLE: During our experiment, I noticed that certain types of music made me move around a
little more or less. I like hip-hop music more, so I was moving along to the beat. I don’t like R&B music
as much so I wasn’t moving around that much. My movement during the music may have affected my
heart rate more than the actual music itself. To fix this problem, I would make myself sit in a chair or
lie down so that my movement while listening to each type of music is limited. Also, I found it difficult
to calculate my heart rate by taking a pulse on my wrist. I may have missed a beat or two, which would
affect my overall average heart rate. To fix this, I would either have a partner take my heart rate for
me or use a stethoscope to take my heart rate.