Hey Everybody, I hope you're having a
good day.
I just wanted to give you some
information on the scientific method.
Hopefully,
This little short video will get across
the major points
of the scientific method that i'd like
you guys to know. In particular there
are six terms that are really really
important and fundamental to
understanding the scientific method, so
let's talk about those now.  First of all,  number one,
every scientific study has a control
group of samples,
and so I'm going to denote that as cg
or control group. Okay, there is also another
term called the experimental
group of samples, and
we'll go into detail about that group of
samples
as well. The third term that i want
you guys to be familiar with
is called, they're called constant
variables, or just
constants for short. Some scientists
also call these
controlled variables.  So, I can put a
a controlled variables just
as another
way to say it.  But, constant variables,
or constants, or constant or controlled
variables.... They all mean the same thing.
Number four is going to be
the independent variable okay
independent variable
all right and that's also called the
manipulated variable by some scientists
uh because scientists choose to
manipulate it we'll talk more about that
in a sec
number five is called the dependent
variable and um
this is uh what scientists should uh
measure
in an experiment more about that in a
section uh and the last term i want you
guys to
to know is is this one called
confounding variables okay
so uh confounding um variables
um are ones that
uh often uh happen or occur in an
experiment they end up
messing up your experiment so um
so let's let's start out with a a you
know a typical
study i would set up um let's take the
example of
a scientist wanted to investigate
whether
a fertilizer was uh you know good at
increasing
the growth of plants okay so uh in a
typical study we
we'd set up two groups okay so um
there'd be a group of samples we'll call
this uh my control group
of samples and here i would have just a
bunch of
you know kind of potted plants with you
know your old jaw some bushes
and we'd have have replicates um
of of this several several pots with
this you know same kind of
plant okay and we call this the control
group of samples so here's sample one
sample two sample three three different
plants three is usually a minimum in
a real scientific study and um this
group of plants um
would get no fertilizer so we would
sometimes maybe call this the
no fertilizer okay group so there's your
no fertilizer and we'd be
doing a study um to to check whether
fertilizer is
is actually working we'd have to have
also a fertilizer
group all right and this fertilizer
group would be my experimental group of
samples
okay and the experimental group i like
to think of this eg
as the exciting group whereas the
control group is
is the ordinary or plain or even boring
group of samples and so uh in this
particular group of samples i'd i'd have
the same pots with
the same plant everything's the same
okay uh right and you you'd have several
of these pots going
a minimum of three you know with their
their plants okay
and uh so here's one two three and then
there was one two three over here but
there's something different about these
plants and so
um let me change my my pen to something
magical inside these
okay pots we have something special
and these pots um that would be a
fertilizer
that is special in there and so um
so that would be a typical study you
have one group of samples this control
group of samples and you'd have an
experimental group of samples and
and you're comparing your in this
experiment what happens with the growth
of plants
say you're measuring the height or the
weight of these plants
uh and then you would um compare
these two groups and and if the
fertilizer group
grows more than the control group then
you can
uh say that the fertilizer was effective
at
increasing uh plant growth um now
things uh these constant variables or
controlled variables
okay these are things that uh we keep
the same
okay so um here we have the same
um and just going back uh you know
sometimes i like to just make this
it's really easy you know control group
is boring group
and experimental group is the uh
exciting group okay of samples and
controlled variables um or constants are
things that we keep the same so what are
we keeping the same between
uh these two again are my cvs my
constant variables and
and that would be like the type of pot
um
how much water you give to both okay so
um i'll just write down a couple
examples like water
okay the amount of water or um
again the type of even the type of plant
the plant that you use etc right you
want to make sure you're
comparing apples with apples not apples
with oranges so to speak
so here we have uh next the independent
variable independent variable
um uh is has another name it's also
called the
manipulated variable okay the
manipulated variable is is one that the
scientist
chooses to change and if you guys know
this delta symbol that's a
symbol for change so i want you to think
about what is the scientist
changing okay between these two groups
and so looking at these two groups right
here what is the scientist
choosing to change that is what the
independent variable always is
what is the one thing being changed
between these two groups
and the one thing that is is different
the fertilizer right so um in this
particular example the independent
variable is the
fertilizer okay so
here is uh the one thing the one thing
that's
that's differing is the um well whether
we have
uh fur you can also call this um
you know whether we have fertilizer or
no fertilizer so you you could call it
the plus minus
treatments okay um some scientists also
like to say okay
it's the amount of the fertilizer
that's differing between here we have
some fertilizer here we have none
um and we have this dependent variable
is our next one and with our dependent
variable
i want you to think um always what what
is the scientist
uh what is being measured okay that's
that's the um
that's the question you need to ask
yourself what is being measured
uh in these pots and these pots what
about the plants
are we measuring and um well it's
it's quite clearly in this particular uh
example
you know it's it's going to be the
growth right
so um growth is what we're measuring
here and i'll just
make sure uh you know it and and growth
uh
usually scientists don't just measure
one plant on this side and one plant on
this side we measure a whole bunch of
plants right
we have a sample size of three or more
okay on this side and
three or more of these samples and we
end up taking an
average so typically we'd say okay this
is going to be
um for instance the average growth in
or it could be the average height in
centimeters
sometimes we don't use height perhaps a
better
indicator of growth might be weight in
which case
we instead of of using uh centimeters
we might use uh grams okay again using
metric units is very important in
science
and um uh finally we have these things
called confounding variables and
confounding variables um are variables
that uh
that mess up i'll just write you know
what's
what could potentially mess up the
experiment okay
and so these are things that mess up
your results and and confound the
experiment they introduce
variability among the replicate samples
so
um what uh what what can happen is in in
this particular experiment
you know say uh you you may have um
i don't know let's pretend you have like
a tree
okay um a tree that that is
in this area where you're doing this
experiment
and um you know over here
you have the sun okay
and the sun represented right there
you know sunlight is coming down but it
hits a tree okay
and so the sun actually only ends up
hitting
these samples but not uh those other
samples
and so this right here i mean if there's
if these ones are are
are shaded from the sun they're not
going to receive
adequate sunlight whereas these ones do
and you might get
a funky result here due to this
confounding variable where your control
group without fertilizer
grows more just because they weren't in
the shade of this tree
so in this example the confounding
variable
is uh the trees shade
cast upon once one group of samples and
not the other
and um anyway we've now gone over the
six
um terms of the scientific method that
i'd like you guys to be familiar with
uh and uh i hope that was uh
clear and you now understand the
scientific method a little bit better
okay have a good day
