Scientific Method Lab

1. The Scientific Method

2. How Science works
• Biology is the study of living things
• Limited to what is observable and testable in a
repeatable way
• Use the tool of the Scientific Method
– Logical and organized
– Appears “cookie cutter” but does allow for
creativity and variation

3. 1. Observe
2. Hypothesis
3. Test/Investigate
4. Report/Analyze
5. Draw Conclusions

4. 1. Observation
• Observe the natural world
• Helps you develop your hypothesis

5. 2. Hypothesis
• Tentative explanation about what you are
investigating
• Needs to be testable
• Today’s question: In what
conditions will Alka-Seltzer
tablets dissolve the fastest?

6. Hypothesis example
• Observation: The butterfly lands on purple
flowers more frequently than yellow flowers.
• Hypothesis: Butterflies are more attracted to
purple flowers than to yellow flowers.

7. Null hypothesis
• Allows statistical testing
• Opposite of the hypothesis
Null hypothesis for butterfly example?
Butterflies have no preference for flowers based
on color.

8. 3. Test your
hypothesis
• Conduct an experiment
• Experimental group: modified
• Control group: standard of comparison
– normal, no manipulation
• Experimental options: (choose 2)
– Cold water, hot water, salt water, acidic water
• Control:
– Room temperature water
– 3 trials per condition (for replication)
– 9 trials total (including control)

9. Experiments have variables
• Specific aspect of an object that can vary
– Three types in an experiment
1. Independent Variable:
changed/manipulated by investigator
2. Dependent Variable: measured, dependent
on the manipulation conducted on the
independent variable
3. Standardized variable: held constant

10. Example variable identification
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.
• What is the independent variable?
• What is the dependent variable?
• What were the standardized variables?

11. 4. Report/Analyze results

12. 5. Draw conclusions
• Based on the results, does the age of the child
impact the time it takes to complete the
puzzle?

13. Hypothesis verses Theory
Hypothesis: A tentative explanation of some
regularity of nature
Theory: a hypothesis that has been tested
numerous times and remains consistent
– Broader in scope
– Predictive power

14. Plan for today
• Design your experiment
– What is your hypothesis/null hypothesis?
– What are the independent and dependent
variables?
– What are standardized variables?
– What is your control group
• Before you conduct the lab your group must
show me, in written form, your materials and
procedures
– Must be approved before you can begin

15. Plan Continued
• Conduct your experiment based on the
methods you devised and had approved.
• Record your data and observations
• You can use the laptop computers to create
visual representations (graphs and tables)

16. A few parameters for your
experiments
• Need to use ¼ tablets per trial
• Can’t use more than 200 ml of liquid to
dissolve the tablet
– Can use a smaller volume

17. Assignment: Lab Report
• Title page: separate sheet
– Include name, instructor name, lab section
• Introduction
– Statement of question
– Hypothesis
• Materials
– List all items used
• Procedure
– Paragraph form
– Enough detail for someone to repeat

18. Assignment: Lab Report
• Results
– Paragraph of text (fastest, slowest, etc.)
• Compare experimental and control
– Table or graph
• Label and include title on figure
• Conclusion
– Restate hypothesis and if you support it or not
• Explain why you reached this conclusion
– Cite your data
– Discuss possible errors