Scientific Method

How can you find a supported answer to an investigative question?

Question

This is the first step of the Scientific Method.

May be asked by the teacher Could be asked by you It should be a problem that can be

testable The question or statement of problem

should include an independent and dependent variable.

Hypothesis This is what you expect to happen

based on your observations and what you already know.

Should begin with “I predict…because…”

It’s OK if it’s wrong – this is how we learn.

It should predict a relationship or trend and should include the independent and dependent variable

Variables

Independent Variable Dependent Variable Controlled Variables

Independent Variable

This is the component of the problem that you are testing to see if it has an effect on something else.

This is the variable that you CHANGE to determine if there is a pattern or relationship between that change and what you are measuring.

A valid experiment has at least 3 levels of the independent variable

Dependent Variable

This is the component of the experiment that is MEASURED

This variable’s measurement DEPENDS on the independent variable

Examples of Independent and Dependent Variables.

How much water gives the greatest plant growth?

Independent Variable: 1 liter, 2 liters, 3 liters of water.

Dependent Variable: the more water is given, the more the plant will grow.

Controlled Variables

These are the components of the experiment that you keep the same throughout the entire experiment.

These are constant and are used to keep the experiment valid.

Standard of Comparison You must choose one of your three

levels of the independent variable for the standard of comparison.

The SOC is used as a point of reference to compare the results of your experiment too.

Think of it as a starting point for discussing and analyzing data.

There is not a correct SOC, but you must rationalize why you picked the one you did

Materials

This is a list of everything a person would need to test the question or problem.

Procedure

This is a STEP BY STEP list of directions needed to test the question.

Should be detailed enough that a stranger could follow the steps to test the question.

Don’t assume that someone else will know what you are talking about.

Should include diagrams Should include repeated trials

Measurement

In science, we measure using the Metric System (SI)

Mass – grams Length – meters Volume – liters Temperature – Celsius Remember prefixes – kilo, centi, milli

Data Table

This is a chart that displays your results. For accurate results data tables must show

multiple trials and an average. Include units in your data table. A general rule of thumb is to have at least 3

trials for most experiments Multiple trials help give you more accurate

results Data Table should be clear enough for a

stranger to understand exactly what is happening in an experiment

Graphs

Once you have gathered your data, you must pick an appropriate graph to display your results

Graphs give your audience an easy visual from which to read the collected data

Types of Graphs

Bar – used to compare data that cannot be connected

Line or Scatter – shows the relationship between an independent and dependent variableX axis – independent Y axis – dependent

Components of Graphs

Title X and Y axis labeled correctly Units included Appropriate scale

Analysis and Interpretation of Data

Compare all data – do not just list data points

Discuss any trends in the data Talk about any unusual data points

Possible Experimental Errors

List possible errors Explain how these errors could have

affected the results of the experiment.

Conclusion

Restate your hypothesis. Confirmation of hypothesis. – Is it accepted

or rejected? Reasons for acceptance or rejection is

explained and supported by the data

Recommendations for Further Use

How will these results be used for further studying and investigation about the problem and issues related to the problem.

Scientific Theory

It takes multiple experiments by many different people for a conclusion to become a theory.

Many scientists have to get similar results and have similar conclusions before something becomes widely accepted.

Compare to multiple sources – if findings are consistent across the board, it’s likely that something true has been discovered.