How To Complete and Experiment and
Write a Lab Report:
Using Questions to Write a
Hypothesis With Clear Independent
and Dependent Variables
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I can…
How to Write a Hypothesis
http://www.myteacherpages.com/webpages/jflynt/portfolio.cfm?subpage=1001394
http://www.accessexcellence.org/LC/TL/filson/writhypo.php
What is a hypothesis?
A hypothesis is a tentative statement that proposes a possible explanation to some phenomenon or event.
A useful hypothesis is a testable, measurable statement, which may include a prediction. In writing a
hypothesis a tentative relationship is stated. If you always ask yourself if one thing is related to
another, then you should be able to test it.
How are hypothesis written?
3 Different Methods
1. RELATIONSHIP METHOD-"IF THE INDEPENDENT VARIABLE IS RELATED TO DEPENDENT VARIABLE, THEN
THE DEPENDENT VARIABLE WILL DO THIS (PREDICTION THAT ANSWERS THE QUESTION) BECAUSE..."
Look at the two examples of hypotheses below:
Question/Purpose: To study how the mass of a car effect the distance it will travel down a ramp.
"If the mass of a car is related to the distance the car will travel down a ramp, then the heavier the
car the farther the car will travel because it has more momentum."
Question/Purpose: How does the color of a shirt effect the heat it absorbs?
"If the color of a shirt is related to the heat it absorbs under a heat lamp, then the darker the shirt
the hotter it will be because dark colors do not reflect light waves."
2. TRADITIONAL METHOD-"IF THE INDEPENDENT VARIABLE (WHAT IS CHANGED), THEN THE DEPENDENT
VARIABLE WILL DO THIS (PREDICTION THAT ANSWERS THE QUESTION) BECAUSE..."
Look at the two examples of hypotheses below:
Question/Purpose: How does the mass of a car effect the distance it will travel down a ramp?
"If a heavier car is run down a ramp then the heavier the car will travel farther than a lighter car
because it has more momentum."
Question/Purpose: To study how the color of shirt effect heat absorption.
"If a black shirt is placed under a heat lamp, then the black shirt will be hotter than a lighter
colored shirt because dark colors do not reflect light waves.”
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Notice that all three of these ways are statements that contain the words “if”, “then”, and
“because”. These words are necessary in a formalized hypothesis. The “if” tells what is being
changed, the “then” tells the prediction of what will happen, and the “because” tells why the scientist
thinks this will happen.
Two Variables in a Hypothesis
Formalized hypotheses contain two variables. One is “independent” and the other is “dependent.” The
independent variable is the one you, the “scientist” change, manipulate, or compare. This is represented
in the upper left hand column of a data table and as the label on the x-axis in a graph. The independent
variable is the “I change” variable; as the scientist, it’s the thing that I’m changing or messing with (or
manipulating) in the experiment! The dependent variable is the one that you measure; it’s the data and
results that you intend to collect (distance the car went). This variable is represented in the upper right
hand column of a data table and as the label on the y-axis in a graph. The dependent (responding)
variable depends on how you manipulate the independent variable. This is found in the “Then” part of the
hypothesis. The “because” statement explains why the scientist thinks the prediction given in the then
statement will happen.
Why Write a Hypothesis
The ultimate value of a formalized hypothesis is it forces us to think about what results we should look
for in an experiment. Of course, the strongest hypotheses also include a measurable prediction. More on
THAT in just a minute!
Measurable Hypotheses
A strong scientific hypothesis not only uses one of the two formalized methods shown above, but it
should also include a measurable prediction about the results. Basically, this means that when you write
a hypothesis, you want to indicate what is being measured. Let’s look at some examples. The prediction
is underlined.
Question/Purpose: How does the mass of a car effect the distance it will travel down a ramp?
“ If the mass of a car is related to the distance the car will travel down a ramp, then the heavier
the car the farther the car will travel because of has more momentum.”
Question/Purpose: How does the color of a shirt effect the heat it absorbs?
“If a black shirt is used, then the darker the shirt will be hotter than a lighter colored shirt
because dark colors do not reflect light waves.”
To make your prediction measurable, you are basically using words that indicate measurement (i.e. travel
farther, temperature). These words indicate that there are numbers that need to be recorded
(whether it is distance a car traveled or the temperature recorded). That is the ultimate goal of any
science experiment, to generate data. With data, a student can begin to find answers to questions and
solutions to problems.
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Dissecting the Hypothesis
Fill in the chart below showing how each part of the hypothesis is different
If
Then
Because
__________________ variable
__________________ variable
or _________________variable
___________________ why
the scientist thinks the
prediction given in the
________________ statement
will happen.
The variable that is
__________________
The variable that is
____________________
__________________
__________________
Read the introduction, example and then complete the Practice Writing hypothesis
problems 1-5 below:
Hypothesis Practice
Answer the following questions by creating a hypothesis.
1. What effect does the size of a rubber ball have on the height it bounces?
If ____________________________________________________________________________
______________________________________________________________________________
then __________________________________________________________________________
______________________________________________________________________________
because _______________________________________________________________________
______________________________________________________________________________
2. What effect does fertilizer have on tomatoes?
If ____________________________________________________________________________
______________________________________________________________________________
then __________________________________________________________________________
______________________________________________________________________________
because _______________________________________________________________________
______________________________________________________________________________
3. What effect does the amount of wings have on the height a rocket flies?
If ____________________________________________________________________________
______________________________________________________________________________
then __________________________________________________________________________
______________________________________________________________________________
because _______________________________________________________________________
______________________________________________________________________________
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4. What effect does playing video games have on blood pressure?
If ____________________________________________________________________________
______________________________________________________________________________
then __________________________________________________________________________
______________________________________________________________________________
because _______________________________________________________________________
______________________________________________________________________________
5. What effect does the size of a coin have on how many water drops it can hold?
If ____________________________________________________________________________
______________________________________________________________________________
then __________________________________________________________________________
______________________________________________________________________________
because _______________________________________________________________________
______________________________________________________________________________
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More Hypothesis Practice
Alka-Seltzer Video
Observation
What happens when an Alka-Seltzer is added to water? _____
______________________________________________
______________________________________________
______________________________________________
______________________________________________
______________________________________________
A student is interested in designing several experiments to
test the factors that effect how quickly an Alka-Seltzer
tablet dissolves in water (solution rate). For each question,
write a hypothesis that could be tested with an
experiment. Be sure each hypothesis is in the proper
“If…then…because…” format. See example below.
Example:
Question/Purpose: What effect does stirring have on solution rate of a tablet?
Hypothesis: If the stirring of water is related to solution rate, then the tablet will dissolve faster in
water that is stirred because when sugar is added to water, it dissolves when it is stirred.
Hypothesis: If a tablet is placed in water that is stirred then the tablet that is stirred will dissolve
faster than a tablet that is not stirred because when sugar is added to water, it dissolves when it is
stirred.
1. Question/Purpose: What effect does the water temperature have on how fast a tablet will dissolve?
Hypothesis: ____________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2. Question/Purpose: What effect does crushing the tablet have on how fast it dissolves?
Hypothesis: ____________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
3. Question/Purpose: What effect does adding soda to the water have on how fast the tablet dissolves?
Hypothesis: ____________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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I can…
Lab-Testing a Hypothesis
Bombs Away
Question: What effect does the height of a water dropper is held at have on the size of a spot the
water drop will make?
Hypothesis: ____________________________________
______________________________________________
______________________________________________
______________________________________________
______________________________________________
Materials:
1- 50ml Beaker
1- Eyedropper
1- Meter Stick
2- Pieces of Construction Paper
Procedure:
1. Fill your beaker with water.
2. Place your meter stick with the 0 cm end on the construction paper.
3. Release one drop of water from 10 cm onto the paper. Be sure the tip of the eyedropper is even with
each of these centimeter marks. Do not hold the dropper too close to the meter stick or the drop will
hit the end of the meter stick.
4. Draw around each wet spot between drops and label the spot with the distance the drop fell and the
trial number. Measure the diameter of the drop in millimeters and record it in the data table. Make
qualitative observations describing what the drop did in the qualitative observation section.
5. Repeat steps 3 and 4, 2 more times. Each time move the meter stick after each drop so the next
drop lands on a different area of the paper.
6. Take a new sheet of construction paper. Place your meter stick with 0 cm end on the construction
paper.
7. Release one drop of water from 50 cm onto the paper. Be sure the tip of the eyedropper is even with
each of these centimeter marks. Do not hold the dropper too close to the meter stick or the drop will
hit the end of the meter stick.
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8. Draw around each wet spot between drops and label the spot with the distance the drop fell and the
trial number. Measure the diameter of the drop in millimeters and record it in the data table. Make
qualitative observations describing what the drop did in the qualitative observation section.
9. Repeat steps 7 and 8, 2 more times. Each time move the meter stick after each drop so the next
drop lands on a different area of the paper.
Qualitative Observations:
Height-10 cm
Trial 1:
Trial 2:
Trial 3:
Height-50 cm
Trial 1:
Trial 2:
Trial 3:
Drawing: Draw the set up of the two different tests below:
10 cm Height
50 cm Height
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Quantitative Observations:
Data Table 1: Height of a Water Dropper and Average Size of a Spot
Height of a Water
Dropper
10 cm height
Trial 1
Trial 2
Trial 3
Average Size of
a Spot
50 cm height
Reflection Questions:
1. What was the independent variable in this lab?
2. What was the dependent variable in this lab?
3. Explain how the height in which the dropper was held affected the size the drop made.
4. Did your hypothesis work? Give evidence to support your answer.
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I can…
_______________________________________
(Title of Lab Report)
Fill in the parts of graphic organizer below, based upon the lab, using complete sentences.
Section A-Question/Purpose, Hypothesis, Materials, Variables
Question/Purpose:
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
Hypothesis (If/then/because statement):
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
Independent Variable (what variable is
being changed…also the top left hand
column of the data table):
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
Materials (bullet point list with how
many of each was used):
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
Dependent Variable (what will
happen…also the top right hand column
of the data table):
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
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Qualitative and Quantitative Observations
Observations are an important part of scientific experiments. Hypotheses are accepted or rejected
based on how well they explain observations. Some observations, such as "the plant turned brown" are
qualitative; these observations have no associated numbers. A quantitative observation includes numbers,
and is also called a measurement.
A measurement is obtained by comparing an object to some standard. Any observation is useful to a
scientist, but quantitative observations are commonly considered more useful. Even if the measurement
is an estimate, scientists usually make both qualitative and quantitative observations in every
experiment.
Qualitative Observations Example from the Bombs Away Lab
Qualitative Observations:
Height-10 cm
Trial 1:
Trial 2:
Trial 3:
Height-50 cm
Trial 1:
Trial 2:
Trial 3:
Drawing-Draw the set up of the two different tests below:
10 cm Height
50 cm Height
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I can…
Quantitative Observations-How to Create a Data Table and Graph
It all starts with the question for the lab. Every lab begins with a question. In that question there is an
independent and dependent variable. In a data table, the independent and dependent variable of that
question is analyzed. How?
A data table is a series of rows and columns that contains the results (dependent variable) of what is
being tested (the independent variable). Therefore, the question of the lab helps set up the data table.
For example, in the Bombs Away lab that was just performed the question of that lab was as follows:
Independent Variable
Dependent Variable
Question: What effect does the height of a water dropper is held at have on the size of a spot the
water drop will make?
Notice how the independent and dependent variable identified in the question is used to set up the data
table for this lab, including the title!
Independent variable from the
question of the lab
Dependent variable from the question
of the lab
Data Table 1: Height of a Water Dropper and Average Size of a Spot
Height of a water dropper
Trial 1
Trial 2
Trial 3
Average Size of
a Spot
10 cm height
50 cm height
The importance of the independent and dependent variable in a lab does not stop with the data table.
The information in the data table is used then to create the graph for the lab. In a graph, the final
results are graphed. Therefore, if three trials are done, it is the average measurement that is
recorded.
Dependent Variable
Average Size of a Spot
(mm)
Graph 1: Height of a Water Dropper and Average Size of a Spot
10 cm height
50 cm height
Height of a Water Dropper
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How to Calculate Average
Foldable-Data Table/Graphing
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Practice-Data Table and Graphing
Using the example lab questions below fill in the missing information in the data table and graph each
data table. Use a single underline to identify the independent variable and use a double underline to
indicate the dependent variable in each question.
Practice #1
Question-What effect does the size of a parachute have on the time a parachute stays in the air?
Data Table 1: Size of a Parachute and Average Time a Parachute Stays in the Air
Trial 1
Trial 2
Trial 3
10 meters in diameter
5.25 min.
6.0 min.
5.45 min.
30 meters in diameter
10.0 min.
12.40 min.
11.30 min
Graph 1:
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Practice #2
Question-What effect does the weight of a car have on the speed it travels down a ramp?
Data Table 1:
Trial 1
Trial 2
Trial 3
15 gram car
14 sec.
16 sec.
18 sec.
55 gram car
5 sec.
8 sec.
6 sec.
Graph 1:
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I can…
Lab-Testing a Hypothesis and Making Qualitative and Quantitative
Observations
Drops on a Penny Lab
Background:. Water contains unique physical features. A special
property of water is surface tension. The surface of the liquid
behaves as an elastic membrane in which surface tension appears,
allowing the formation of drops and bubbles. When water is
dropped on a penny, the surface tension allows the water to form a
bubble dome on the penny.
Question/Purpose: What effect does the side of a penny have on the number of drops it can hold?
Hypothesis (Claim): ______________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Materials:
1 penny
1 beaker with water
1 medicine dropper
1 Paper towel
1 magnifying glass
Procedure:
1. Fill a beaker with water. Take a penny and place it in front of you.
2. Take the medicine drop and fill it up with water from the beaker.
3. Carefully drop water on the penny. Keep count of how many drops of water the penny holds. Record
how many drops the penny held.
4. Dry the penny and repeat step 2 two more times. Record your findings in the data table.
5. Dry the penny and flip it over completing steps 2-4.
6. Average your three trials for a more accurate idea of how many drops of water a penny will hold.
Qualitative Data:
Look at each side of a penny with a magnifying glass. Draw each side in the boxes below.
Heads Side
Tails Side
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Describe what happened as water was dropped on each side of the penny.
Heads Side:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Tails Side:
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Quantitative Data:
Data Table 1: _________________________________________________________
Trial 1
Trial 2
Trial 3
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I can…
_______________________________________
(Title of Lab Report)
Fill in the parts of graphic organizer below, based upon the lab, using complete sentences.
Section A-Question/Purpose, Hypothesis, Materials, Variables
Independent Variable (what variable is
being changed…also the top left hand
column of the data table):
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
Dependent Variable (what will
happen…also the top right hand column
of the data table):
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
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Section B-Procedure
22
23
Section C-Qualitative and Quantitative Data
24
25
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Writing Analysis
Once the data table and graph have been done, the data is then analyzed. The purpose of this is to
explain the results of the data as recorded in the data table and graph. The goal of this is to show the
relationship between the independent and dependent variable.
Fill in the data table below with the results from the “Drops on a Penny Lab”. Then write analysis for
the results following the instructions given in the graphic organizer below the data table.
Data Table 1:
Section D-Analysis
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I can…
Identifying the Experimental Error and Writing the Conclusion
Scientists often make many measurements during experiments. As in just about every human endeavor,
errors are unavoidable. In a scientific experiment, this is called experimental error. Systematic errors
are part of the experimental setup, so that the numbers are always skewed in one direction. For
example, a scale may always measure one-half of an ounce high. Random errors occur because a
measurement is not made precisely. For example, a stopwatch may be stopped too soon or too late. To
correct for this, many measurements are taken and then averaged. Experiments always have a margin of
error associated with them.
In an experiment, if a result is inconsistent with the results from other samples and many tests have
been done, it is likely that a mistake was made in that experiment. The inconsistent data point can be
thrown out.
Let’s Practice Identifying Source Error
Observe the following experiments performed by the teacher and record the experimental errors. In
the box to the right explain why it is a source error. Below identify how the lab could be improved
(another way of saying what can be done to eliminate the source error next time).
Ball Bounce
Question: Can a smaller ball bounce
higher than a basketball?
Source Error
Why?
____________________________________
____________________________________
___________________________
____________________________________
___________________________
____________________________________
___________________________
____________________________________
28
Rubber Band
Question: Which type of rubber band flies
the longest distance?
Source Error
___________________________
___________________________
___________________________
Why?
____________________________________
____________________________________
____________________________________
____________________________________
____________________________________
Mass and Speed
Question: How does the mass affect the
speed of a car?
Source Error
___________________________
___________________________
___________________________
Why?
____________________________________
____________________________________
____________________________________
____________________________________
____________________________________
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Write out the conclusion using the “Drops on a Penny Lab.” Follow the instructions in each box on the
conclusion graphic organizer.
Section E-Conclusion
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Come Fly with Me Lab
Background: There are three forces that act upon a
paper airplane. Those forces are lift, weight, and
drag. Drag is the aerodynamic force that opposes
an aircrafts motion through the air. Lift is the
force that holds an aircraft in the air. Lift is
caused by wind going over and under the wings.
Finally, weight is a force caused by the gravitational
attraction of the Earth.
In this lab, we want to find out what effect does the weight of an airplane have on its flight?
In other words, does the weight of an airplane affect how far a paper airplane can travel?
Problem/Question: Does the weight of a paper airplane affect how far it flies?
Hypothesis: ______________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Materials:
1-Sheet of 8.5 x 11 paper
1-Metric measuring tape
1-Paper Clip
Procedures:
1. Build a basic airplane
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2. Take the basic airplane, standing behind the starting line, gently fly the plane.
3. When the plane lands, measure the distance with the measuring tape and record that number
in the data table.
4. Repeat two more times and record the data in the data table. Then calculate the average
distance flown.
5. Take the basic airplane and add a paper clip in the middle along the bottom of the plane.
6. Repeat steps 1-4.
Qualitative Observations: (How did the plane fly for each trial? Be sure to be specific!)
___________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Drawing:
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Quantitative Data:
Data Table 1:
Trial 1
Trial 2
Trial 3
Lab Report: On the next several pages is the format for lab reports will be written in junior
high. Using the Paper Airplane Lab, which was done in this note packet, we will write a lab
report together. Be sure to keep this note packet and all its contents in the Lab Report
Section of your science binder. This will be a resource for you throughout this year
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_______________________________________
(Title of Lab Report)
Fill in the parts of graphic organizer below, based upon the lab, using complete sentences.
Section A-Question/Purpose, Hypothesis, Materials, Variables
Independent Variable (what variable is
being changed…also the top left hand
column of the data table):
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
Dependent Variable (what will
happen…also the top right hand column
of the data table):
_______________________________
_______________________________
_______________________________
_______________________________
_______________________________
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Section B-Procedure
35
36
Section C-Qualitative and Quantitative Data
37
38
Section D-Analysis
Section E-Conclusion
39
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