# Pretest What is science?

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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 questions Making observations
Forming hypothesis Testing hypotheses

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

hypothesis An explanation for an observation an “educated” guess
must 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 DISPROVEN example: 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 GROUP
Group 2: Music for 1 hour a day Group 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 rained Your INTERPRETATION of what you observed

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