Pretest

What is science?What is the difference between a

hypothesis, a theory, and a law?What are the steps of the scientific

method?What is a control group, an independent

variable, and a dependent variable?

What is Science?

What is Science?

Asking questionsMaking observationsForming hypothesisTesting hypotheses

What is the difference between a hypothesis, a theory, and a law?

hypothesis

An explanation for an observation an “educated” guessmust be testable!!!

theory

A hypothesis which has been tested numerous times

and found to be correct (can explain observations)

but not yet “proven”

law

Laws are theories which have been extensively tested

and have NEVER BEEN DISPROVENexample: law of gravity

What are the steps in the Scientific Method?

The Scientific Method

The Problem The Procedure The Data The Conclusion

Ask a Question

Form a TESTABLE hypothesis

Test the hypothesis with an experiment

Collect data

Assemble into charts

Accept or reject hypothesis

Example of the Scientific Method

Suppose you want to see if playing music makes a bean plant grow taller.

What would your hypothesis be?

Design an experiment to test your hypothesis. Say that you have 50 seedlings to start with.

Playing Music Makes Bean Plants Grow Taller

• Play music for all 50 seedlings.

• Measure: How high do the plants grow?

• Results: The plants grew an average of 10 inches.

• What is the problem with this experiment?

Playing Music Makes Bean Plants Grow Taller

Group 1: No music CONTROL GROUP

Group 2: Music

Measure: How high do the plants grow?

Variables

Group 1: No music CONTROL GROUPGroup 2: Music for 1 hour a dayGroup 3: Music for 2 hours a day

How would you plot your results? What TWO things are changing?

What are the two variables?

How much music was played?

How tall did the plants grow?

Variables

How much music was played? Independent variable (manipulated)

How tall did the plants grow? Dependent variable (responding)

The dependent variable DEPENDS on the independent variable.

How tall the plants are DEPENDS on how much music is played.

What is wrong with this experiment?

You decide to see if taking vitamin “Q” will make your pet rats go through a maze faster. You feed one group of rats vitamin “Q” and give them extra food and water. You give the rest of your rats no vitamin, and only normal amounts of food and water.

CARDINAL RULE!!!!!!!!!!!!!!!!!!

Only test ONE variable at a time!!!!!!!

What is wrong with this experiment?

You have two rats. You give one vitamin “Q” and the other gets no vitamin.

Sample size is too small.

Observations and Inferences

You go the movies one afternoon. When you come out of the theater, you notice that the sidewalk is wet. “It must have rained,” you think to your self.

What did you OBSERVE?What did you INFER?

Observation: the sidewalk is wet Information gathered using one or more of

your senses

Inference: it rainedYour INTERPRETATION of what you

observed