What do scientists do?

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How does science work?

The Scientific Method

Scientific Tools

1. computer technology2. internet3. libraries4. scientific method and experiments5. models6. statistics7. pictures/maps/graphs

Hypothesis

a statement that uses a few observations

an idea based on observations without experimental evidence

Theoryuses many observations and has

loads of experimental evidence

can be applied to unrelated facts and new relationships

flexible enough to be modified if new evidence introduced

Lawstands the test of time, often without change

experimentally confirmed over and over

can create true predictions for different situations

has uniformity and is universal

Scientists use experiments to search for cause and effect relationships in nature.

What is a controlled experiment?

controlled experimentKeep everything the same except for

the single variable being tested.

Variables

A variable is something that can be changed in the experiment. It is what you are testing.

Everything else must be the same and only one variable or condition is altered or changed.

Control Group

A control group receives the same attention as the test groups, however, it will not be influenced by the variable the other groups are testing.

example• QUESTION:  How will the amount of

fertilizer used  affect plant growth?

• HYPOTHESIS:  Increased dosages of fertilized will cause greater growth in tomato plants.

• TEST VARIABLE:  The amount of fertilizer used.

Does fertilizer make a plant grow bigger?

• Amount of fertilizer measured in grams.

• Growth of the plant measured by its height• • Growth of the plant measured by the number

of leaves

Controls• Same size pot for each plant

• Same type of plant in each pot

• Same type and amount of soil in each pot

• Same amount of water and light

• Make measurements of growth for each plant at the same time

"The many variables above can each change how fast a plant grows, so to insure a fair test of the fertilizer, each of them must be kept the same for every pot."

http://videos.howstuffworks.com/hsw/5886-scientific-method-controlled-experiment-video.htm

Variables

independent variable

dependent variable

Independent Variable

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

• A good experiment has only one independent variable.

• The scientist changes the independent variable and observes what happens.

Dependent Variable

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

Units of Measure

REVIEW

I. scientific methodII. hypothesisIII. theoryIV. natural lawV. controlled experimentVI. variablesVII. units of measure