Identifying Variables

What is a variable? Different parts that make up an experiment.

Types of Variables There are 2 main types of variables: Independent Variable: The variable that is being tested or changed by the scientist. In every experiment there is only one! Dependent Variable: The variable that might change because of what the scientist changes – what is being measured

Another type of Variable Control Variable: These variables are kept constant throughout the whole experiment. Not to be confused with a control group! Control groups are a group that do not receive the same treatment as the experimental groups so you have something to compare it to.

The nice thing is…. Your hypothesis can TELL you what your variables are! Hypothesis: an educated guess of what will happen in a certain situation. Often written as an if, then statement.

Write a hypothesis for the given question. I wonder if I take good notes in Mrs. Holland’s class if I will get good grades on my quizzes? I wonder if I will get sick if I don’t ever wash my hands?

Identify the Variables from this hypothesis. Ex. If I drink Mountain Dew before bed, then I will not sleep very much. IV: Drinking Mountain Dew DV: the amount of sleep

Use this hypothesis to identify the variables: Practice Use this hypothesis to identify the variables: If I leave all the lights on all day, then my electric bill will be expensive IV: ______________________ DV: ______________________

There will be less fur on my couch if I brush my cat more. IV: ______________________ DV: ______________________

WHITE BOARD PRACTICE Send one person from each table to get a white board, marker, and eraser for each person.

Identify the Variables Elizabeth wanted to test if temperature affected how fast milk goes bad and curdles. She left 3 gallons of milk in a room temperature closet, a fridge, and a oven that was turned on low heat. She then measured how rotten the milk was after 10 days. IV: ____________________________________ DV: ____________________________________ What are the control variables?

Identify the variables A group of students chose to study accelerations. They used a specific type of toy car, that weighed the same, and made a ramp from a wooden board. They held one end of the ramp on the floor at various angles, which they measured using a protractor. Then they used a meter stick to measure how far the cars went off the ramp.

Identify the variables Students wanted to test how much food allows a certain type of goldfish to grow the fastest. One tank of goldfish is fed once a day, a second tank is fed twice a day, and a third tank is fed three times a day. The fish’s weights are recorded daily for a six week period.