Independent Variable/Dependent Variable
A variable being tested in an experiment; the one variable that is changed.
independent variable
A variable that is kept constant (not changed) by the scientist in an experiment.
controlled variable
the name of the type of graph used in our pendulums experiments.
picture graph
How many independent variables should be changed when doing a controlled experiment?
One independent variable at a time.
a push or a pull that can cause something to start moving, stop moving, change it's speed or direction of movement.
force
The outcome or results of an experiment; what you find out.
dependent variable
Added force when releasing the pendulum was this type of variable in our Pendulums experiment.
controlled variable
best fit line
How many controlled variables should be changed when doing a controlled experiment?
None. They should all be kept the same.
The force that pulls everything towards the center of the Earth.
gravity
Bob mass was this type of variable in our pendulums experiment.
independent variable
Harry wanted to see whether or not the type of string used had an effect on how many swing cycles a pendulum made in 15 seconds. He conducted a standard test on a pendulum with a bob mass of 1 penny; 38 cm long, released at desk top height. He then changed the string to a piece of fishing wire and conducted his test again.
Did Harry control all of the variables he should have?
Yes.
Which variable is graphed on the X axis?
the independent variable
Viraaj and Eliot rolled a ball down a ramp and recorded how far the ball travelled in 15 seconds. When they shared their results with the class, they found that they had very different results from the rest of the class.
What did they need to do in order to be more sure of their results?
they should have conducted more tests
Ms. Ritter's cat, Teddy, is sitting on the kitchen table. Gravity is pulling down on Teddy. What is providing the force that pushes up on him?
the table.
The number of swing cycles the pendulum made in 15 seconds was this type of variable.
dependent variable
Mrs. Ritter wants to test which type of dog treats her dog Roxy prefers. She sets up an experiment by placing 3 Milk Bone dog biscuits in one bowl, and 3 Snausage snacks in another bowl. She releases Roxy and records which dog treats Roxy eats first.
What is one controlled variable mentioned above?
Controlled variables: Roxy, number of treats
Which variable is graphed on the Y axis?
The dependent variable
Mr. Papp wanted to conduct a controlled experiment to see whether the type of ball, softball or tennis ball, made a difference in how far his 1st grade students could throw. He had each student throw a softball 3 times and recorded the distance thrown.
What should Mr. Papp do next?
He should have each student throw the tennis ball 3 times and record the results.
Mrs. Deinstadt's Spanish book is sitting on her desk, not moving. Why isn't the book moving?
Forces are balanced.
Mr. Burt wants to know whether drinking the energy drink Red Bull or Monster will make it more difficult to fall asleep. He designs an experiment to test this problem statement.
In this experiment, the type of energy drink consumed is considered what type of variable?
The independent variable.
Mrs. Trenholm wants to know whether a student read longer during the morning or afternoon. She gave the student a book at 10:00 in the morning and had them record the amount of time they read the book before stopping for a break. She then gave the book to the student at 2:00 in the afternoon and had them record the time they read.
Did Mrs. Trenholm control all of her variables correctly?
Yes.
What do the "D" and the "I" stand for in the mnemonic DRY MIX?
D stands for dependent variable; I stands for independent variable
Samantha wants to test how sunlight affects the growth of plants, so she places one of them near a window and one of them in a dark room. The plant by the window receives 1 cup of fertilizer each day, and the plant in the dark room receives no fertilizer. Each of the plants receives a cup of water each day.
Did Samantha control all the variables she needed to?
No, there is more than one independent variable.
A pendulum made from a penny attached to a string is swinging back and forth. What two forces are acting on the pendulum?
the force of the string is applying a sideways force and gravity is pulling it down.