# Do Now - PowerPoint PPT Presentation

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Do Now. You have 5 minutes to answer the following question(s). When you are done take out your binder and turn to the notes section. What factors affect your ability to make an “A” in a class? What factors affect how fast a plant grows?. Announcements/ Expectations.

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Do Now

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### Do Now

You have 5 minutes to answer the following question(s). When you are done take out your binder and turn to the notes section.

• What factors affect your ability to make an “A” in a class?

• What factors affect how fast a plant grows?

### Announcements/ Expectations

• You will start seeing grades go in this weekend.

• Prepared for class

• Binder, divider and composition notebook

• Class Points

## Variables and Hypothesis

### What is a variable?

• Scientists use an experiment to search for cause and effect relationships in nature.

• A variable is any factor, trait, or condition that can exist in differing amounts or types. An experiment usually has three kinds of variables: independent, dependent, and controlled.

### Independent Variable

• Also called the manipulated variable.

• This is the variable that the scientist will manipulate to see how it affects the dependent variable.

• The independent variable is the one that is changed by the scientist.

• To insure a fair test, a good experiment has only one independent variable.

• As the scientist changes the independent variable, he or she observes what happens.

### Dependent Variable

• Also called the responding variable.

• Are the result of something that the scientist has changed

• Is actually being measured in the experiment

• The scientist focuses his or her observations on the dependent variable to see how it responds to the change made to the independent variable.

### Controlled Variable

• Also called the constant variable

• The control variable will be the one that does not change.

• Most experiments have more than one controlled variable.

• The control variable is something that is constant and unchanged in an experiment.

### Form a Hypothesis

Hypothesis: an educated guess or prediction; an “if, then” statement

If independent/manipulated variable, then dependent/responding variable.

### Example

• Mandy set up an experiment to show the relationship between plant growth and amount of water given to the plants.

• The stated problem was "Does the amount of water affect the growth of bean seeds?”

• Mandy's hypothesis was written in "if-then" format:

• If I don't water my plants, then they will not grow.

• Independent variable- Amount of water

• Dependent variable- Plant growth

### Use this hypothesis to identify the variables

If I leave all the lights on all day, then my electric bill will be high.

IV: ______________________

DV: ______________________

If I drink Mountain Dew before bed, then I will not sleep very much.

IV: ______________________

DV: ______________________

If I brush my cat more, then there will be less fur on my furniture

IV: ______________________

DV: ______________________

### Now read the following experiment and identify the independent and dependent variables and write a hypothesis

Elizabeth wanted to test if temperature affected how fast milk goes bad and curdles. She left 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.

Hypothesis: ______________________________

IV: ____________________________________

DV: ____________________________________

### Independent Practice

Worksheet Example

Hypothesis:______________________________

IV: ____________________________________

DV: ____________________________________

### Exit Ticket

What is an independent variable?

What is a dependent variable?

What is a hypothesis?