Formatting a testable hypothesis
What Is a Real Hypothesis?
A hypothesis is a tentative statement that
proposes a possible explanation to some phenomenon or event. A useful
hypothesis is a testable statement, which may include a prediction. A
hypothesis should not be confused with a theory. Theories are general explanations
based on a large amount of data. For example, the theory of evolution applies
to all living things and is based on wide range of observations. However, there
are many things about evolution that are not fully understood such as gaps in
the fossil record. Many hypotheses have been proposed and tested.
When Are Hypotheses Used?
The key word is testable. That is, you will
perform a test of how two variables might be related. This is when you are
doing a real experiment. You are testing variables. Usually, a hypothesis is
based on some previous observation such as noticing that in November many trees
undergo color changes in their leaves and the average daily temperatures are
dropping. Are these two events connected? How?
Any laboratory procedure you follow without a
hypothesis is really not an experiment. It is just an exercise or demonstration
of what is already known.
How Are Hypotheses Written?
Chocolate may cause pimples.
Salt in soil may affect plant growth.
Plant growth may be affected by the color of the
light.
Bacterial growth may be affected by temperature.
Ultra violet light may cause skin cancer.
Temperature may cause leaves to change color.
All of these are examples of hypotheses because
they use the tentative word "may”. However, their form is not particularly
useful. Using the word “may” does not suggest how you would go about providing
supporting evidence for the hypothesis. If these statements had not been
written carefully, they may not have even been hypotheses at all. For example,
if we say, "Trees will change color when it gets cold." we are making
a prediction. Or if we write, "Ultraviolet light causes skin cancer."
could be a conclusion. One way to prevent making such easy mistakes is to
formalize the form of the hypothesis.
Formalized Hypotheses example: If skin cancer is
related to ultraviolet light , then people with a high exposure to uv light
will have a higher frequency of skin cancer.
If leaf color change is related to temperature ,
then exposing plants to low temperatures will result in changes in leaf color.
Notice that these statements contain the words ,
if and then. They are necessary in a formalized hypothesis. But not all if-then
statements are hypotheses. For example, "If I play the lottery, then I
will get rich." This is a simple prediction. In a formalized hypothesis, a
tentative relationship is stated. For example, if the frequency of winning is
related to frequency of buying lottery tickets. "Then" is followed by
a prediction of what will happen if you increase or decrease the frequency of
buying lottery tickets. If you always ask yourself if one thing is related to
another, then you should be able to test it.
Formalized hypotheses contain two variables. One
is "independent" and the other is "dependent." The
independent variable is the one you, the "scientist" control and the
dependent variable is the one that you observe and/or measure the results
The ultimate value of a formalized hypothesis is
it forces us to think about what results we should look for in an experiment.
Notice there are two parts to a formalized
hypothesis: the “if” portion contains the testable proposed relationship and
the “then” portion is the prediction of expected results from an
experiment. An acceptable hypothesis
contains both aspects, not just the prediction portion.
Investigation 1: Conducting a Biological
Experiment
Purpose: to learn how to use the scientific method
by conducting an experiment.
You have learned so far that scientists use the
"scientific method" in solving problems. Although there is no set
order to the sequence, a scientific investigation may include some or all of
the following activities; literature search, stating the problem, writing a
hypothesis, designing an experiment, collecting data/observation, verification,
graphing data, interpreting data, and forming a conclusion.
For today’s experiment you will develop a
formalized hypothesis based upon the part II experiment of the lab exercise on
page 5 of the lab manual (including both testable relationship and prediction).
Each lab group will Set-up both experiments; pages 4 and 5 of the lab
manual. During the next week each lab
group will collect data in tables . Once
the data is collected your group will have to summarize the data and represent
the results using a table and figure.
Step 1: Introduction material before beginning an
experiment.
Refer to page 4 of your lab manual for a description of the
experiment. Notice that page 4 includes
introductory information that explains the underlying hypothesis of spontaneous
generation.
A. State the Problem (this is
usually a general question but often
does not include a proposed relationship)
What is the general
question addressed by Procedure 1?
(notice this is not a formalized hypothesis; it
does not contain any information to identify the independent or dependent
variable. This step is not included in a
formal lab report introduction section.)
B. Literature Search (this
section is required to explain the reason
for a proposed relationship [the hypothesis])
What background information is required to explain
your formalized hypothesis? For the formal lab report you need to find
appropriate cited sources to support your hypothesis.
___________________________________________________________________
___________________________________________________________________
C. Writing a Hypothesis
Procedure 1 page 4 of the lab manual
Read the procedure on page 4 of the lab manual to
determine the independent and dependent variables. Write a formalized
hypothesis. Include the dependent and
independent variables.
Procedure 2 page 5 of the lab manual
Read procedure II on page 5 of the lab manual to
determine the independent and dependent variables. Write a formalized
hypothesis. Include the dependent and
independent variables.
1. Are the
independent and dependent variables the same for both procedures?
2. Are the
hypotheses for procedure 1 and procedure II the same?
If not what relationship does procedure II test?
Experimental Design: Follow the instructions on
page 4 and 5 of your lab manual.
The following tables are meant to aid in
collecting the raw experimental data. Do
not use these tables in the final lab report; follow the example table in the
handout on how to write a results section.
*Note this is not the final table to use in your
formal lab report.
Data/Observations
Table 1.
Time – series data for your own group.
Record the dependent variable each assigned day.
Procedure 1:
Dependent variable?_________________________
surface sampled
Day __
Day __
Day __
Day __
Table 2. Time – series data for your own
group. Record the dependent variable
each assigned day. Each group must have a sediment score for each treatment for
four days; this data will be used to generate a time-series graph for the lab
report.
Procedure 2 Dependent variable=__Sediment Score_
Flask opening treatment
Day __
Day __
Day __
Day __
Interpretations and Conclusions
Why should the results from each group be combined
with other class group data? before analyzing the results for a lab report?
___________________________________________________________________
What was the independent variable of Procedure
I?____________ Procedure II?
______________________________ What was the dependent variable of Procedure
I?______________ Procedure II?_____________________________
Why were five Petri dishes necessary Procedure I ?
What is the purpose of including the fifth Petri dish if the lid was never
removed?
___________________________________________________________________
___________________________________________________________________
Write a conclusion for Procedure II that will
support your group’s hypothesis (Describe how the independent and dependent
variable are related).
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
Check the class standard flasks for the sediment
scale:
During next week’s lab each group will present
their results and fill in a class data table, see below. The class data table
is the data that must be used for the Chi-square test in your lab report.
Table 3.
Bio 100 class data for Procedure II, page 5 of the lab manual. The sediment scores are based upon the score
assigned to each flask on day 5. n= 6.
Flask opening treatment
Sediment score on Day 5.
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
No Cotton plug
Cotton plug
Cotton plug w/
straight
glass tube
Cotton plug w/
curved
glass tube
🧪 1. Ice
Cube Melting Rates
💡 The
Concept
Does the starting temperature of water change how
fast an ice cube melts?
🔍
Hypothesis
If an ice cube is placed in hot water, then it
will melt faster than in room-temperature water because the increased thermal
energy causes a faster phase change.
🧪 How to
Test
Get 3 identical cups
Fill them with:
Hot water
Room-temperature water
Cold water
Add equal-sized ice cubes to each
Start a stopwatch
Record how long each ice cube takes to melt
completely
🧪 2.
Temperature and Dissolving Speed
💡 The
Concept
How does water temperature affect how fast a
substance (like sugar) dissolves?
🔍
Hypothesis
If sugar is added to hot water, then it will
dissolve faster than in cold water because higher temperature increases
molecular movement, breaking the sugar apart more quickly.
🧪 How to
Test
Prepare 3 cups of water at:
10°C (cold)
25°C (room temp)
60°C (hot)
Add 1 tablespoon of sugar to each
Stir at the same speed
Time how long it takes to fully dissolve
🧪 3. Water
Evaporation
💡 The
Concept
Does heating water increase evaporation?
🔍
Hypothesis
If water is placed in a warm area, then more of it
will evaporate compared to water in a cool area because warmer molecules escape
into the air more easily.
🧪 How to
Test
Measure 100 mL of water into 2 identical bowls
Place:
One in a warm, sunny spot
One in a cool, dark place
Leave for 24 hours
Measure how much water is left
🧪 4.
Temperature and Water Density (Floating vs. Sinking)
💡 The
Concept
How does temperature affect water density and
mixing?
🔍
Hypothesis
If food coloring is dropped into hot water, then
it will spread faster than in cold water because warm water is less dense and
molecules move more freely.
🧪 How to
Test
Fill:
One glass with hot water
One glass with ice-cold water
Add 1 drop of food coloring to each
Do not stir
Observe and time how long it takes to spread
🌡️ Simple
Temperature Understanding
🧠 Key Idea
Temperature tells us how fast molecules are
moving:
🔥 Hot → very
fast
🙂 Warm → medium
❄️ Cold → slow
📊 Quick
Temperature Guide
Category °F °C Description
❄️ Cold Below 50°F Below
10°C Icy, may have ice
🙂 Warm 90–110°F 32–43°C Feels like skin/bath
🔥 Hot 130–211°F 54–99°C Steamy, too hot to hold
👀 How to
See Temperature Differences
🎨 Food
Coloring Test
Hot water → mixes
fast
Cold water → slow
streaks
🌊 Density
Test
Hot water = lighter
Cold water = heavier
🌡️
Thermometer
Most accurate way to measure temperature
🎯 Big Idea
(All Experiments)
All four experiments show the same rule:
👉 Higher
temperature = faster particle movement
This explains:
Faster melting
Faster dissolving
Faster evaporation
Faster mixing🌡️ Understanding Temperature
(Simple Explanation)
Temperature = how fast tiny particles (molecules)
move
Hot water →
particles move fast
Warm water →
particles move medium speed
Cold water →
particles move slow
👉 This is
called kinetic energy (movement energy)
🧪
Experiment 1: Ice Cube Melting
💡 Concept
Does temperature change how fast ice melts?
🔍 What
happens
Hot water → melts
ice fast
Room temp → melts
medium
Cold water → melts
slow
🧠 Why
Hot water has more energy →
transfers heat to ice faster → ice
melts quicker
🧪 Steps
3 cups: hot, room temp, cold
Add same size ice cube to each
Start timer
Record melting time
🧪
Experiment 2: Dissolving Sugar
💡 Concept
Does temperature affect dissolving speed?
🔍 What
happens
Hot water → sugar
dissolves fast
Cold water →
dissolves slow
🧠 Why
Fast-moving water molecules break sugar apart
quicker
🧪 Steps
3 cups: 10°C, 25°C, 60°C
Add 1 tablespoon sugar
Stir same speed
Time how long it disappears
🧪
Experiment 3: Evaporation
💡 Concept
Does heat increase evaporation?
🔍 What
happens
Warm area → more
water disappears
Cool area → less
evaporation
🧠 Why
Faster molecules escape into the air as gas
🧪 Steps
Measure 100 mL water into 2 bowls
Put one in warm/light
Put one in cool/dark
Check after 24 hours
🧪
Experiment 4: Density & Mixing
💡 Concept
Does temperature affect how water mixes?
🔍 What
happens
Hot water → color
spreads quickly
Cold water → color
moves slowly
🧠 Why
Hot water is less dense + molecules move faster
🧪 Steps
One glass hot, one cold
Add 1 drop food coloring
Do NOT stir
Observe + time spreading
🌡️ Easy
Temperature Guide
Category °C What it feels like
❄️ Cold Below 10°C Icy,
sharp feeling
🙂 Warm 32–43°C Like
bath water
🔥 Hot 54–99°C Too
hot to hold
👀 How to
See Temperature Differences
1. Food Coloring Test
Hot → mixes
instantly
Cold → stays in
streaks
2. Movement Idea
Hot water = “busy, fast crowd”
Cold water = “slow, quiet crowd”
3. Thermometer
Most accurate way to measure temperature
🎯 Big Idea
(All Experiments Together)
All your experiments show the same rule:
👉 Higher
temperature = faster particle movement
This causes:
Faster melting
Faster dissolving
Faster evaporation
Faster mixing
🧩 If Your
Goal Is Learning (Your Answer)
Since you said:
“understand temperature from hot, warm, cold”
These experiments are perfect because they let
you:
See it (color spreading, ice melting)
Measure it (time, volume)
Understand it (particle movement)
🔬 The
Scientific Method
The scientific method works in steps:
Observation – Notice something
Question – Ask why or how
Hypothesis – Make a testable guess
Experiment – Test the idea
Conclusion – Decide if you were right
👉 Yes,
brain composition and measurements can be used in hypothesis testing🧪
Hypothesis Practice
💡 Simple
Idea
If hot water moves fast, then cold water must move
slow.
👉 This is
about particle movement (kinetic energy):
🔥 Hot
water → fast movement
❄️ Cold
water → slow movement
🧊 Ice Cube
Example
🔍
Hypothesis
If an ice cube is placed in hot water, then it
will melt faster than in cold water because the water molecules are moving
faster and transfer heat more quickly.
🌡️ Boiling
Water Temperature (Formula Idea)
💡 Key Fact
Water boils at:
100°C
212°F
👉 This is
the temperature where water changes from liquid to gas (boiling).
🧪
Hypothesis Example
If heat is added to water until it reaches 100°C,
then it will begin to boil and turn into steam.
💧 The
“Water Hypothesis” (Different Meanings)
The term “water hypothesis” can mean different
things depending on the subject.
🌍 1.
Origin of Earth’s Water Hypothesis
💡 Idea
How did Earth get its water?
🔍 Main
Theories
🪨 Native
Origin Theory
Earth’s materials already had hydrogen
Water formed naturally inside Earth
☄️ Asteroid
/ Comet Delivery
Ice from space hit Earth
Water was delivered from comets and asteroids
💧 2.
Liquid Polymorphism Hypothesis (Water Anomalies)
💡 Idea
Water behaves in unusual ways.
🔍 Key
Point
Ice floats (most solids sink!)
Water may exist as two liquid forms:
High-density
Low-density
👉 These
forms may mix and change at tiny (microscopic) levels
🧬 3.
Aquatic Ape Hypothesis (Waterside Hypothesis)
💡 Idea
Humans may have had a semi-aquatic past.
🔍 Suggests
Early humans:
Walked in water (bipedalism)
Lost body hair
Developed body fat for warmth
👉 This
idea is debated and not widely accepted by all scientists
🧪 4. Basic
Science Education (Water Experiments)
💡 Idea
“Water hypothesis” is often used in simple
experiments.
🔍 Example
Hypothesis
If salt is added to water, then the boiling point
will increase.
👉 This is
easy to test and shows how science works.
🎯 Big Idea
All of these examples use the same rule:
👉 A
hypothesis = a testable “if…then…” statement
Examples:
If water is hotter →
particles move faster
If particles move faster → changes
happen quicker
🧠 1. How
many cells are in the brain?
The brain is made of two main types of cells:
Neurons → send
electrical signals
Glial cells (glia) → support
and protect neurons
👤 Human
Brain
About 171 billion total cells
Around 86 billion neurons
Around 85 billion glial cells
🐾 Animal
Brains (examples)
Cat → about
250 million neurons (cerebral cortex)
Dog → about
530 million neurons
African elephant → about
257 billion neurons
👉
Different animals have different brain sizes and abilities
❤️ 2. How
much blood is in the brain?
Blood is always moving, not staying still.
🧠 Brain
Blood Volume
About 75 to 150 milliliters in the brain at one
time
🔄 Blood
Flow
About 20% of your total blood supply goes to the
brain every minute
👉 This
supplies:
Oxygen
Nutrients
Energy
📊 3. What
else needs to be measured?
Scientists measure more than just cells.
🔗 Synapses
Connections between neurons
Humans have about 100 trillion synapses
⚡
Neurotransmitters
Chemical messengers (example: dopamine)
Help brain cells communicate
🧠 Brain
Activity
Electrical signals
Energy use during thinking and tasks
🧪 4. Can
this be turned into a hypothesis test?
👉 Yes!
Any measurable brain feature can be tested.
✔️ A good
hypothesis must:
Be testable
Compare two or more things
🧪 Example
Hypotheses
🧠
Hypothesis 1🌡️
Hypothesis About Boiling Water
🔍
Hypothesis
If hot or warm water is heated, then it will reach
a rolling boil faster than cold water because it has a smaller temperature gap
to reach 100°C (212°F).
👉 This
means:
Hot water starts closer to boiling
Cold water has to heat up more
🧪 How to
Test This Hypothesis
You can test this using a simple kitchen
experiment.
🧰 What You
Need
Two identical pots
A cooking thermometer
A timer or stopwatch
Water
🔬 Steps to
Perform the Test
1. Prepare Samples
Measure the same amount of water:
One pot = cold tap water
One pot = hot tap water
2. Record Starting Temperatures
Use a thermometer to write down:
Starting temperature of cold water
Starting temperature of hot water
3. Heat the Pots
Place both pots on the stove
Use the same heat level for both
4. Time the Boil
Start the timer when heating begins
Watch for a rolling boil
Big bubbles rising constantly
5. Compare Results
Step A: Temperature Change
Calculate:
Boiling point = 100°C
Subtract starting temperature
👉 Example:
Cold water: 10°C → needs
+90°C
Hot water: 60°C → needs
+40°C
Step B: Compare Time
Which pot boiled faster?
Does it match your hypothesis?
🔬 The
Science of Boiling
Water boils when:
👉 Vapor
pressure = atmospheric pressure
🧠 What
This Means
Water molecules are moving
Heat makes them move faster
When they move enough → bubbles
form and escape
🔥 Why Hot
Water Boils Faster
Molecules already have higher kinetic energy
Less extra heat is needed
So boiling happens sooner
🎯 Big Idea
👉 Hot
water boils faster because:
It starts closer to boiling
It needs less energy
Its particles are already moving faster
❓ If You
Want to Improve Accuracy
You can think about:
What thermometer you are using
Gas stove or electric stove
How much water (cups or quarts)
🌡️ Why Hot
Water Boils Faster
Hot water reaches boiling faster than cold water
because it starts closer to the required temperature (100°C / 212°F).
👉 Key
idea:
Hot water needs less heating
Cold water needs more heating
🔬
Scientific Rationale
🌡️ Thermal
Gap
At sea level, water boils at 100°C (212°F)
Hot water (~50°C) → needs
+50°C
Cold water (~10°C) → needs
+90°C
👉 Cold
water has a bigger gap to cover
🔥 Heat
Transfer Rate
Heat moves faster when the temperature difference
is bigger
Cold water heats faster at first
But later, both heat at similar rates
👉 Cold
water cannot “catch up” because it needs more total energy
🧪
Experimental Procedure
Follow these steps carefully:
⚖️ 1.
Equalize Equipment
Use two identical pots
Use two identical burners
🧴 2.
Calibrate Volumes
Add 1 quart (946 mL) cold water to one pot
Add 1 quart (946 mL) hot water to the other
🌡️ 3.
Establish Baseline
Use a digital thermometer
Record starting temperatures
🔥 4. Apply
Constant Heat
Turn both burners to High at the same time
⏱️ 5.
Monitor Boiling
Start timer when heat begins
Stop when:
Rolling boil (big bubbles), OR
Temperature reaches 100°C (212°F)
📊 6.
Analyze Data
Compare how long each pot took to boil
⚙️ Factors
Influencing Results
🏔️ Altitude
Higher altitude = lower boiling point
Example: ~95°C in high places like Denver
🫕 Lid
Usage
Lid traps heat and steam
Makes water boil faster
❄️ Mpemba
Effect
This applies to freezing, not boiling
Sometimes hot water freezes faster than cold
Does not affect this experiment
🎯 Big Idea
👉 Hot
water boils faster because:
It starts closer to boiling
It needs less energy
Even though cold heats faster at first, it cannot
catch up
❓ Next
Step (Optional)
If you want to refine your experiment, you can
think about:
Your altitude/location
What material your pots are made from (steel,
copper, aluminum)
If an animal has more neurons in its cerebral
cortex, then it will solve puzzles faster than an animal with fewer neurons.
🧠
Hypothesis 2
If a person is doing a learning task, then blood
flow to the hippocampus (memory area) will increase by more than 30%.
🎯 Big Idea
👉 The
brain can be studied scientifically by measuring:
Cells
Blood flow
Connections
Activity
And then testing ideas using the scientific
method.
