1. Designing Experimental Investigations

2. 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

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

4. 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

5. 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

6. Investigations are designed to test hypotheses
Experimental Investigation
Question
Hypothesis

7. 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

8. 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.

9. 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

10. 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

11. After you have collected data
Analyze your results
Relationships
Patterns
Trends

12. 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

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

14. Communicate your new knowledge
Lab reports
Posters
Periodicals