Designing Experimental Investigations

There are two general types of scientific investigations: Descriptive Experimental Observational; describes Does not look for relationships between variables Nothing is changed Often leads to experimental investigations Involves the control and manipulation of variables Tests a hypothesis

Experimental investigations usually begin with Observations Often come from descriptive investigations Deliberate Accidental

affect another variable? Observations lead to Testable Questions Questions that can be answered by science Independent Variable How does a variable affect another variable? Dependent Variable

A hypothesis is often formed Question Professional scientists do not always have a hypothesis. Educated guess about how the independent variable will affect the dependent variable. Hypothesis

Investigations are designed to test hypotheses Experimental Investigation Question Hypothesis

To test a hypothesis you need to Change one variable The INDEPENDENT or MANIPULATED variable while Keeping other variables from changing The CONTROLLED variables or CONSTANTS

Helps make sure your results are consistent and accurate. You also need to Repeat the experiment multiple times. Helps make sure your results are consistent and accurate.

During the investigation Collect data in a chart or table Charts & tables keeps your data organized and easy to understand Descriptive Title (includes independent & dependent variables) Name of Independent Variable Name of Dependent Variable   Trial 1 2 3 4 5 Average variable

Display your data so that it is easy to understand Graphs Use averages to reduce the amount of data on a graph. Title: IV vs DV   Dependent Variable Independent Variable

After you have collected data Analyze your results Relationships Patterns Trends

Relationships Patterns Trends Check to see what the independent variable does to the dependent variable Relationships Change in the dependent variable caused by the independent Patterns Data repeats itself regularly Trends A consistent increasing or decreasing change

Data Draw conclusions Supported Or Did Not Support Hypothesis Answered Testable Question Sometimes more research is needed Never “right” or “wrong”

Communicate your new knowledge Lab reports Posters Periodicals