Download ind and dep variables plus hypothesis

 Independent & dependent variables
 Observations & Inferences
 Qualitative & quantitative data
 Steps of the scientific method
 Weather notes: fronts, air masses
vocabulary, hurricanes, symbols
 Newton’s Laws of Motion
Before we can perform an experiment
designed to answer this question, we must
determine the independent and dependent
variable.
For an experiment to have valid results, there
can be only one independent variable.
THIS IS IMPORTANT!
 The independent variable is the variable that
you, as the scientist, will vary to observe the
effect; it is the cause in the problem…
 The independent variable is sometimes
called the manipulated variable because it is
the variable the scientist manipulates.
 The dependent variable is the variable that
you, as the scientist, will measure and record
– it’s the data of the experiment
 The dependent variable is sometimes called
the “responding” variable because it is the
variable that responds to the independent
(or manipulated) variable; it is also called
the “effect” in the problem.
To determine the independent and dependent
variable, identify the two things that will
(might) change:
 lack of sleep
 weight of an individual
Once you know the two things that are (or might be)
changing, arrange them in a question like this:
In this experiment, does the lack of sleep depend on
weight gain?
OR
Does weight gain depend on lack of sleep?
The variable that depends on the other is the
dependent variable.
A lack of sleep depends on weight gain?
OR
that weight gain depends on a lack of sleep?
Weight gain depends on the lack of sleep so
weight gain is the dependent variable.
It’s important to understand that you don’t
yet have to know if weight gain depends on a
lack of sleep – you just need to identify
which variable you will be manipulating and
which variable will respond to your
manipulations.
What effect does being raised on a fish farm
have on a salmon’s length?
What two factors are being studied?
salmon’s length
raised on a fish farm
What effect does being raised on a fish farm
have on a salmon’s length?
Does being raised on a fish farm depend on
the salmon’s length?
OR
Does the length of the salmon depend on
being raised on a fish farm?
The length of the salmon depends on being
raised on a fish farm
Independent Variable?
raised on fish farm
Dependent Variable?
length of salmon
On the following slides, write down the
research question in your notes and then
discuss with your partner what you believe
the two factors that will (might) change are.
After you agree on the two factors, see if you
can agree on which one is the independent
variable and which one is the dependent
variable.
Two factors being studied?
presence of music
number of tomatoes grown
independent variable?
 presence of music
dependent variable?
 number of tomatoes
Two factors being studied?
frequency of exercise
number of infections with cold virus
independent variable?
 exercise
dependent variable?
 number of colds
over a specified time
period
Two factors being studied?
use of cell phones while driving
number of automobile accidents
involved in
independent variable?
 use of cell phones
while driving
dependent variable?
 number of auto
accidents involved
in
 Once you know the independent and
dependent variables, writing a hypothesis
statement is easy!
 A hypothesis simply combines the
independent and dependent variables into a
prediction statement.
Research Question: What effect does salt have
on the boiling point of water?
Independent Variable:
adding salt
Dependent Variable:
boiling point of water
IV: adding salt to H2O
DV: boiling temp
A good hypothesis statement is an “if” “then”
statement.
If salt is added to water, then the boiling point
of water will increase.
If salt is added to water, then the boiling point
of water will increase.
The independent variable is the “if” part of
the hypothesis and the dependent variable is
the “then” part.
 a statement that predicts something
 testable
 an “if” “then” statement
a question
a statement that has words in it like
 maybe
 probably
 might
 A hypothesis might also have a “because”
section
 In the prior example, the “because” would
sound like this:
 If salt is added to water, then the boiling
point will increase because salt is an ionic
compound and ionic compounds are known
to elevate boiling points.
 What is the effect of wing size on the falling
speed of a rotocopter?
 What are the two factors?
 wing size
 falling speed
 Which factor is the independent variable?
Dependent variable?
 ind v: wing size
dep v: falling speed
 ind v: wing size
dep v: falling speed
If the wing size is increased, then the falling
speed of the rotocopter will decrease.
or
If the wing size is increased, then the falling
speed of the rotocopter will decrease
because increased wing size will result in
increased air resistance.
 What effect does sandpaper have on a block
of wood’s sliding velocity?
 Two factors?
 sandpaper
 sliding velocity
 Ind V and Dep V?
 IV: sandpaper
DV: sliding velocity
 IV: sandpaper
DV: sliding velocity
 If a block of wood is pulled on a sandpaper
surface instead of a wooden surface, then the
sliding velocity will decrease.
 or
 If a block of wood is pulled on a sandpaper
surface instead of a wooden surface, then the
sliding velocity will decrease because the force
of friction of the sandpaper will be greater.
More Great Science from The Science Vault
If you enjoyed this powerpoint, you might like these other best-selling products:
Chemical Bonding Go Fish: making chemical bonding less abstract and more fun;
several different games allow for differentiation for all ability levels, grades 8 – 12
Scientific Method/Experimental Design Unit: a full-fledged unit with powerpoints,
worksheets, and quizzes – great to start off the year, or review throughout the year
Continental Drift and Plate Tectonics Powerpoint – 50 interactive slides that
introduce continental drift and plate tectonics. Includes links to websites for flash
animations
The Life Cycle of Stars Powerpoint – gorgeous photos and videos bring this
powerpoint alive for your students
© Jan Parker, The Science Vault, 2009 – for purchaser’s classroom use only. Please do not distribute. For more great
science and class management materials, follow me at http://www.thesciencevault.net or on twitter @thesciencevault
or head on over to my TpT store: http://www.teacherspayteachers.com/Store/The-Science-Vault