Learning Objectives

• Define the scientific method and name the steps in the correct order.

• Explain the difference between independent, dependent, and controlled variables.

• Describe the difference between quantitative and qualitative data.

• Explain how a scientific law is different from a scientific theory.

Key Vocabulary

Scientific Method

A process scientists use to produce reliable results and answer questions in their investigations.

Hypothesis

A testable prediction, often written as an “If...then...” statement, based on a well-researched question.

Independent Variable

The one factor that is changed by the scientist during an experiment; it is the cause.

Dependent Variable

The factor that is measured or counted as data; it is the effect of the change.

Scientific Theory

A well-substantiated explanation based on experiments; it is the most logical explanation for observations.

Scientific Law

A rule of nature that describes a pattern, often summarizing related observations from many experiments.

What is the Scientific Method?

• The scientific method is a step-by-step process scientists use for investigations.

• Its goal is to find reliable answers to questions about nature.

• It is a flexible guide for exploring questions through observation and experiments.

• Science is using this method to learn more about the natural world.

The Scientific Method

• Ask a question and research to understand the problem you are investigating.

• Form a testable hypothesis and conduct an experiment to test your prediction.

• Record all your measurements and analyze the data to draw a conclusion.

• Share your results with others and retest to ensure they are reliable.

Identifying Variables

• The factor you change is the independent variable.

• The factor you measure is the dependent variable.

• All other factors are kept the same.

Data and Graphing

Quantitative Data

• ​It is data that you can measure with different tools.

• ​​It is expressed in numbers, like from rulers or thermometers.

• ​This data type is often very reliable for scientific results.

Qualitative Data

• ​It is data you describe using your five senses.

• ​​This data describes qualities or characteristics of an object.

• ​It is not based on any kind of numerical measurements.

Graphing Data

• ​Scientists use graphs to easily display all their collected data.

• ​​An acronym to remember for graphing data is DRY MIX.

• ​Dependent variables go on the Y-axis; independent go on X-axis.

Scientific Law vs. Theory

Scientific Law

• Describes a pattern in nature that is observed repeatedly.

• It summarizes observations but does not explain the reason why the pattern exists.

• An example is the Law of Gravity, which describes how objects fall.

Scientific Theory

• Provides a detailed explanation for why something happens in the natural world.

• It is supported by a large amount of evidence from many experiments.

• An example is the Theory of Natural Selection, explaining how species evolve.

Common Misconceptions

Summary

• The scientific method is a process used to investigate and answer questions.

• Experiments test independent variables to see their effect on dependent variables.

• Data is either quantitative (numbers) or qualitative (descriptions). Use DRY MIX for graphs.

• A scientific law describes a pattern, while a scientific theory explains it.