Scientific Method Georgia CTAE Resource Network Instructional Resource Office To accompany curriculum for the Georgia Peach State Career Pathways April.

Scientific Method

Georgia CTAE Resource Network Instructional Resource OfficeTo accompany curriculum for the Georgia Peach State Career Pathways April 2009, Kayla Calhoun & Dr. Frank Flanders

Objectives

List steps of the scientific method Explain how different variables are

used in an experiment Contrast qualitative and

quantitative data Demonstrate knowledge of scientific

method by performing an experiment

What is the scientific method?

Principles and procedures for the systematic pursuit of knowledge involving recognition and formulation of a problem, collection of data through observation and experiment, and formulation and testing of hypotheses

Steps of the Scientific Method:

1. Ask a Question2. Make Observations & Research Topic3. Form a Hypothesis4. Design & Perform an Experiment5. Collect & Analyze Data6. Draw Conclusions7. Make Recommendations

Step 1: Ask a Question

Recognize a problem and develop a question to be answered by experimentation

Step 2: Make Observations & Research Topic

Make observations Do background research on the

topic Find the best way to experiment Don’t repeat past mistakes

Step 3: Form a Hypothesis

After researching the topic, develop a hypothesis (an educated guess) about the outcome of your experiment

Basic format: “If I do this (independent variable), then this (dependent variable) will happen.”

Step 3 (continued):Variables

Independent variable (IV): the experimenter changes this variable; should only change one thing per experiment

Dependent variable (DV): value depends on the independent variable; its measure determines if hypothesis was correct or incorrect

All other conditions should remain constant in all trials so that any changes to the DV can be attributed to variation in the IV

Step 4:Design & Perform an Experiment

Procedure should be clear and easy to reproduce by others

Experimental group: independent variable is altered

Control group: standard of comparison; “no treatment” group

Only one factor is changed at a time in the experimental group, keeping all other conditions constant.

Step 5:Collect & Analyze Data

Collect measurements and analyze data Procedure may be modified Qualitative data relies on the senses and

reveals changes in behavior Quantitative data relies on measurable

facts and figures Repeat experiment a few times to

maximize accuracy of results. Each replication is referred to as a trial.

Step 6:Draw Conclusions

Based on analysis of results, accept or reject the hypothesis Accept: test it again using a different

variable. Reject: form a new hypothesis and go

through the process again.

Step 7:Make Recommendations

Recommend further experimentation and possible improvements to the procedure.

Consistent results may lead to…

Theory: uses many experimental observations, can be applied to new situations, can be modified if new data appears; cannot be proven, only disproven

Law: confirmed in every experiment, creates true predictions for different situations, uniform, and universal

Pasteur’s Spontaneous Generation Experiment

The following slides explain how Louis Pasteur used the steps of the scientific method to disprove the theory of spontaneous generation.

Pasteur’s Spontaneous Generation Experiment

Question: Can a nonliving substance (broth) produce living cells (bacteria)?

Observation: bacteria appeared in spoiled broth, and people thought the broth became bacteria, or produced it

Hypothesis: If cells (bacteria) arise from nonliving substances, they will appear in sterile broth.

Pasteur’s Spontaneous Generation Experiment

Experiment: Pasteur prepared a nutrient broth and

exposed it to bacteria, contaminating it. He placed equal amounts of the broth into two

long-necked flasks. One had a straight neck, and the other had a swan neck.

Pasteur’s Spontaneous Generation Experiment

Experiment: He boiled both flasks of broth to kill any

existing bacteria (sterilization) and then left them at room temperature.

Pasteur’s Spontaneous Generation Experiment

Observation: Bacteria appeared only in the control flask with the straight neck; dust and condensed water accumulated in the swan necked flask.

Analysis: Dust carrying bacteria was able to fall into the straight-necked flask, but gravity forced it to stop in the neck of the swan-necked flask. Bacteria only

contaminated the flask in which dust was able to enter.

Pasteur’s Spontaneous Generation Experiment

Conclusions: The shape of the flask affected the

amount of bacteria in the broth; therefore, the broth did not produce the bacteria.

The hypothesis of spontaneous generation is rejected.

Summary

Steps of the Scientific Method: Ask a Question Make Observations & Research Topic Form a Hypothesis Design & Perform an Experiment Collect & Analyze Data Draw Conclusions Make Recommendations