The Scientific MethodThe Scientific Method1

Theory vs Hypothesis• Theory- generalization that explains a body of known facts or

phenomena• Hypothesis- a testable prediction based on research and

observations

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The Scientific method is a systematic way of gathering evidence to support ideas and theories that help explain the natural world around us.

The Scientific MethodThe Scientific Method

Steps of the Scientific MethodSteps of the Scientific Method

Step 1: State the ProblemStep 1: State the Problem

• What are we trying to figure out?

• It is usually stated as a question containing words like “How”, “Why”, and “What”

• The problems that are investigated are found using observations 4

Steps of the Scientific MethodSteps of the Scientific Method

Step 2: Research & HypothesisStep 2: Research & Hypothesis

• A Hypothesis is a testable prediction based on research and observations.

• The hypothesis is the experimenter’s idea of what will happen.

• Before a hypothesis is formed, there must be prior research or observations taken to make a prediction about the problem.

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Forming a HypothesisForming a Hypothesis• When an experimenter has an idea of what will occur, they will

write this idea as an “If... then…” statement.

• Examples:• If I place a plant in sunlight, then it will

grow better.• If I eat a lot of Twinkies, then I will gain a

lot of weight.

• A hypothesis MUST BE TESTABLE

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Steps of the Scientific MethodSteps of the Scientific Method

Step 3: The ExperimentStep 3: The Experiment• In order to test the hypothesis, an experiment must be

conducted.

• Consists of a list of materials and the procedure (steps of the experiment)

• Experiments must be reproducible so other scientist can try them for themselves.

• There are four specific parts to an experiment.7

• Independent Variable (Mix)Independent Variable (Mix)• Also called the controlled or manipulated variable• What the experimenter controls during the experiment to test the

hypothesis• X axis

• Dependent Variable (Dry)Dependent Variable (Dry)• Also called the measured or responding variable• What you’re trying to find• Y axis

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The Parts of an ExperimentThe Parts of an Experiment

• ConstantsConstants• Everything else in the experiment besides the variables

• Held the same to make sure only the independent variable is affecting results

• Control Control

• A standard for comparison

• Usually a trial of the experiment where the independent variable is totally absent

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The Parts of an ExperimentThe Parts of an Experiment

Steps of the Scientific Steps of the Scientific MethodMethod

Step 4: Data AnalysisStep 4: Data Analysis• After the experiment has been conducted, data must be organized

to make a conclusion

• Data should first be organized in a data table.

• Then, data can be visually organized using a graph in order to more easily form a conclusion

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Precision vs Accuracy• Accuracy- the condition or quality of being true, correct, or

exact• Precise- the extent to which a given set of measurements of

the same sample agree with their mean

Qualitative vs Quantitative• Qualitative- non-numerical system observations

• Color, smell• Quantitative- numerical system observations

• Time, mass, volume

Steps of the Scientific MethodSteps of the Scientific MethodStep 5: Making a ConclusionStep 5: Making a Conclusion• After the experiment has been completed, a conclusion must be

formed. • Every conclusion must give evidence for the new idea or outcome. • It should contain the following:

1. Restatement of the Hypothesis2. Brief description of lab organization3. Comment on the data collected4. Statement of the trend or pattern in the data collected5. Statement discussing whether your hypothesis was

accepted or rejected and what you can do further.

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Read the first scenario and answer the next 4 questions.

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What is the best hypothesis for the scenario?A. If Sandy uses more soil in a cup, then the plants will grow

taller.B. If Sandy plants fewer seeds in a cup, then the plants will

grow taller.C. If Sandy plants more seeds in a cup, then the plants will grow

taller.D. If Sandy uses less soil in a cup, then the plants will grow

taller.

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What is the independent variable?A. Amount of soilB. Size of cupC. Number of seedsD. Height of plants

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What is the dependent variable?A. Amount of soilB. Size of cupC. Number of seedsD. Height of plants

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What is the constant?

A. Amount of soilB. Size of cupC. Type of seedsD. Number of seeds

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Read the second scenario and answer the next 5 questions.

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What is the best hypothesis for the scenario?A. If more compost is used, then the plants will grow taller.B. If the plants receive more water, then the plants will grow

taller.C. If the plants receive more sunlight, then the plants will grow

taller.D. If the plants receive older compost, then the plants will grow

taller.

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What is the independent variable?A. Amount of waterB. Age of compostC. Height of plantsD. Amount of compost

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What is the dependent variable?A. Amount of waterB. Age of compostC. Height of plantsD. Amount of compost

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What is the constant?

A. Amount of waterB. Age of compostC. Amount of compostD. Height of plants

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What is the control?

A. The flat with 3 month old compostB. The flat with 6 month old compostC. The flat with no compostD. The flat that received no sunlight

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