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Scientific Method

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1. Observation Leads to collecting data Data: The information collected from an experiment.

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Asking a Question Based on observations; one or more

questions are generated

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2. Hypothesis hypo (less than) thesis (theory) Explanation for what you have seen and

recorded An educated guess? A question or statement that can be tested. A suggested answer to a well-defined

scientific question - ( an explanation on trial)

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Forming a Hypothesis Statement is testable if evidence can be

collected that either does or doesn’t support it

It can never be proven beyond doubt Often must be refined and revised or

discarded

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Predicting To test hypothesis it is necessary to make

predictions that logically follows from the hypothesis

A statement made in advance that states the results that will be obtained from testing the hypothesis

Often in the form of an “if-then” statement

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3. Experiment

A procedure to test a hypothesis, under controlled conditions – conducting a controlled experiment.

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3 Kinds of Variables

Controlled Variable – a variable that is not changed Also called constants Allow for a “fair test”

Controls ensure that all variables in the experiment are the same except for the variable being tested.

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3 Kinds of Variables

DRY MIX

Independent Variable – something that is changed or can be manipulated by the scientist What is tested (the treatment) What is manipulated

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3 Kinds of Variables Dependent Variable – something that might

be affected or responds to by the change in the independent variable What is observed What is measured The data collected during the

investigation (the result of the treatment)

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For Example:

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Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.

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Identify the variables

in this investigation.

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What was the independent variable?

Ages of the students Different ages were tested by the scientist

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What was the dependent variable?

The time it takes to put the puzzle together The time was observed and measured by the

scientist

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What was a controlled variable?

Same puzzle All of the participants were tested with the

same puzzle. It would not have been a fair test if some had

an easy 30 piece puzzle and some had a harder 500 piece puzzle.

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Another example:

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An investigation was done with an electromagnetic system made from a battery and wire wrapped around a nail. Different sizes of nails were used. The number of paper clips the electromagnet could pick up was measured.

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What are the variables in this investigation?

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Independent variable:

Sizes of nails These were changed by the scientist

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Dependent variable:

Number of paper clips picked up The number of paper clips observed and

counted (measured)

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Controlled variables:

Battery, wire, type of nail None of these items were changed

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One more:

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The higher the temperature of water, the faster an egg

will boil and cook.

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Independent variable – temperature of water Dependent variable – time to cook an egg Controlled variable – type of egg

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Last one:

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The temperature of water was measured at different depths

of a pond.

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Independent variable – depth of the water Dependent variable – temperature Controlled variable – thermometer

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Designing Investigations

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The greater the amount of soap in a soap and water mixture, the bigger a soap bubble can be blown.

Design an investigation to test this hypothesis. Identify the variables What exactly will be changed? How will it be

changed? What exactly will be measured? How will it be

measured?

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The farther a ball drops, the higher it will bounce.

Design an investigation to test this hypothesis. Identify the variables What exactly will be changed? How will it be

changed? What exactly will be measured? How will it be

measured?

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4. Collecting Data Data is data, it isn't right or wrong -

presented in tables, charts, notes or diagrams.

Two Types Quantitative Qualitative

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Quantitative Dataquantity - measured in numbers

Qualitative Data quality - measured in words

(descriptions)

Types of Data

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5. Analyzing Data Make interpretations of data by graphing

data, correlating data with facts, using mathematical analysis etc.

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6. Conclusions Report data - put your numbers into words.

Answer: What was found out and how do you know it to be true? How did it relate to your hypothesis? Did it support or fail to support?

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Analyze process and repeat All valid data is reproducible

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Communication Share the results of their studies with other

scientists Publish findings in journals or at scientific

meetings Sharing of information is essential to

scientific process Subject to examination and verification by

other scientists Allows scientists to build on the work of

others

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Forming a Theory A theory may be formed

after many related hypotheses have been tested and supported with experimental evidence

A broad and comprehensive statement of what is thought to be true

Supported by considerable evidence

Ties together related hypotheses

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Theory Explanation supported by a large amount of

evidence obtained from many different investigations over a long period of time.

Common Misconception: Theory defined as a guess is not the scientific definition.

Example: Theory of Evolution

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Law “Proven” theory - a theory explains a law Examples: Law of Gravity, Law of

Conservation of Energy, Law of Conservation of Matter

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Measurements

We will be using SI (International System of Measurement ) units or metric system when possible --- get use to it --- the WHOLE world uses it except us (USA)

Examples: length in meters, volume in liters, temperature in Celsius, mass in grams and time in seconds.

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