IV DV Constant Control Review

Variables and Hypothesis Review

Practice with components of scientific investigations

Variables

• The Independent variable (IV) is the factor that the investigator changes. CAUSE

• The Dependent variable (DV) is the factor that changes in response to the IV. EFFECT

• The constants are the factors that are kept the same

Multiple Choice

When experimenting with the growth of a plant, a scientist uses three (of the same type of) plants, two different fertilizers, equal light, and equal water. What type of variable is the fertilizer?

• Dependent

• Control

• Independent

• Compound

Multiple Choice

Mr. S. sets up an experiment to see how the mass of a ball affects the distance it rolls off a ramp. Identify the independent variable.

• distance traveled by the ball

• mass of the ball

• height of the ramp

• color of the ball

Multiple Choice

What is the IV in this question: How does the distance from an eye chart affect the number of letters that are recognized on a line

• The eye chart

• The distance from the eye chart

• The line

• The number of letters recognized

Multiple Choice

Amari wants to test the effect of the amount of light energy on plant growth. What is the dependent variable?

• Type of plant

• Plant container

• Amount of light

• Plant growth

Multiple Choice

Kay wants to determine if the length of the string affects the number of times a pendulum will swing back and forth in 10 seconds? What is the IV and the DV

• IV: pendulum, DV: number of seconds

• IV: length of string, DV: times the pendulum swings

• IV: times the pendulum swings, DV: number of seconds

• IV: length of string, DV: number of seconds

Hypothesis

• A hypothesis is a suggested solution to a problem

• Written as an if... then... statement

• Example: If I increase the amount of water I give my plant, then in will increasein height.

Multiple Choice

Which is a valid hypothesis for this example: Ahleayah wants to investigate if the amount of fertilizer used on a field will affect the number of earthworms found there.

• If there are earthworms, then there will be fertilizer.

• If the amount of fertilizer is increased, then the number of earthworms will decrease

• Can earthworms live in fertilized fields?

• Fertilizer kills earthworms

Multiple Choice

What is a valid hypothesis for this example: Dante wants to investigate if the amount of oxygen in the water will have an effect on the oyster population.

• If the amount of oxygen in the water is decreased, then the number of oysters will decrease.

• Can oysters breathe oxygen in the water?

• Oysters will turn blue when exposed to oxygen.

• If there are oysters in the water, then there will be less oxygen.

Multiple Choice

A custodian notices some dirty tables and wants to know which cleaner is the best to use. He tests three different cleaners and looks at how well they clean compared to tap water. What is the independent variable?

• type of cleaner

• tap water

Experimental Group

• Receives treatment or test material

• For example: One plant receives fertilizer

• Fertilizer is the test material, so this plant is the experimental group.

Control Group

• Does not receive the treatment or test material

• For example: One plant does not receive fertilizer

• Not receiving the fertilizer makes this plant the control group

Multiple Choice

This part of the experiment serves as a basis of comparison; the one variable being tested has been omitted. 

• experimental group
• control group
• data
• variables

Multiple Choice

A custodian notices some dirty tables and wants to know which cleaner is the best to use. He tests three different cleaners and looks at how well they clean compared to tap water. What is the control group?

• type of cleaner

• tap water

Multiple Select

The two groups in a controlled experiment are -

• Control Group

• Experimental Group (Test)

• Independent Variable

• Dependent Variable

• Constant(s)

Constant

• Does not change

• Stays the SAME

• For example: same height, same amount of water are constants

Multiple Choice

What are all the things that are kept the same in an experiment?

• controls
• data
• constants
• independent variables

Multiple Choice

To test the effects of roller coaster height on speed, what factors should you keep constant? 

• Number of people on it 
• Time of day
• Air temperature