Daily Challenge, 9/29
Scientists often make generalizations –
broad statements or rules that usually
apply in most situations. Think about
the gum experiments we did last week
and the results we are sharing in class.
Write at least two generalizations about
how the mass, volume, and/or density
of gum changes when you chew it.
“In general, the…”
Variables in a Scientific Experiment
Independent Variable – the “cause” or thing you
manipulated/changed to see what would happen
Dependent Variable – the “effect” or thing that
responded to the independent variable
Controlled Variables – variables that are held
constant to make a fair test so you can be sure
the independent variable was the only cause
The experimental control group is the unchanged
independent variable you use for comparison –
don’t confuse it with controlled variables.
Example Experiment
Some students do an experiment to figure out what kind of acid
dissolves limestone the fastest. They get 8 pieces of limestone
that are the same size and shape and measure the mass of
each one. Two pieces are put into a plastic container with 100
mL of plain water. Two pieces are put into a plastic container
with 100 mL of hydrochloric acid. Two pieces are put into a
plastic container with 100 mL of nitric acid. Two pieces are put
into a plastic container with 100 mL of acetic acid. All the plastic
containers are kept in the same place. Every 6 hours, each
piece of limestone is weighed to determine its mass.
Identify the Independent Variable.
A.type of rock B.size of container
C.amount of liquid
D.type of liquid E.weight of rock dissolved F.container location
Example Experiment
Some students do an experiment to figure out what kind of acid
dissolves limestone the fastest. They get 8 pieces of limestone
that are the same size and shape and measure the mass of
each one. Two pieces are put into a plastic container with 100
mL of plain water. Two pieces are put into a plastic container
with 100 mL of hydrochloric acid. Two pieces are put into a
plastic container with 100 mL of nitric acid. Two pieces are put
into a plastic container with 100 mL of acetic acid. All the plastic
containers are kept in the same place. Every 6 hours, each
piece of limestone is weighed to determine its mass.
Identify the Dependent Variable.
A.type of rock B.size of container
C.amount of liquid
D.type of liquid E.weight of rock dissolved F.container location
Example Experiment
Some students do an experiment to figure out what kind of acid
dissolves limestone the fastest. They get 8 pieces of limestone
that are the same size and shape and measure the mass of
each one. Two pieces are put into a plastic container with 100
mL of plain water. Two pieces are put into a plastic container
with 100 mL of hydrochloric acid. Two pieces are put into a
plastic container with 100 mL of nitric acid. Two pieces are put
into a plastic container with 100 mL of acetic acid. All the plastic
containers are kept in the same place. Every 6 hours, each
piece of limestone is weighed to determine its mass.
Identify the Controlled Variables.
A.type of rock
B.size of container
D.type of liquid
E.rocks in water
C.amount of liquid
F.container location
Example Experiment
Some students do an experiment to figure out what kind of acid
dissolves limestone the fastest. They get 8 pieces of limestone
that are the same size and shape and measure the mass of
each one. Two pieces are put into a plastic container with 100
mL of plain water. Two pieces are put into a plastic container
with 100 mL of hydrochloric acid. Two pieces are put into a
plastic container with 100 mL of nitric acid. Two pieces are put
into a plastic container with 100 mL of acetic acid. All the plastic
containers are kept in the same place. Every 6 hours, each
piece of limestone is weighed to determine its mass.
Identify the Experimental Control Group.
A.type of rock
B.size of container
C.amount of liquid
D.type of liquid
E.rocks in water
F.container location
Daily Challenge, 10/1
A student does an experiment to see
how the amount of watering affects
how tall a bean plant grows.
What is the independent variable?
What is the dependent variable?
What would be a good experimental
control group for this experiment?
Name 5 other variables that should
be controlled or held constant.
Intro to Earth Science Quiz
TOMORROW
TOPICS to Review HOW to Review
scientific method
variables – independent,
dependent, & controlled
branches of Earth Science
geology, meteorology,
oceanography, astronomy
metric system
standard units & conversions
density – how to calculate it
scientific models
types, purpose, limitations
read through & organize
worksheets, notes, handouts
review notes, assignments, &
challenges on Blackboard
review chapter 1 in Holt text
answer review questions