Scientific Method: The principles that guide scientific research and experimentation. Definitions of scientific method use such concepts as objectivity of approach to and acceptability of the results of scientific study. Objectivity indicates the attempt to observe things as they are, without falsifying observations to agree with some preconceived world view.

Scientific Method Acceptability is judged in terms of the degree to which observations and experimentations can be reproduced. "Scientific Method," Microsoft® Encarta® Encyclopedia 99. © Microsoft Corporation. All rights reserved. Is your experiment valid (good) if no one else can repeat it and get the same results?

Scientific Method So, why do we conduct experiments? What gets us started? Curiosity. Observations. Questions.

Scientific Method Once a question is formed, what is the next next step? Hypothesis: Your best reasoned answer to the question. You should not write your hypothesis using personal pronouns. It should be written as an objective statement. It is best to use an if, then statement.

Scientific Method For example: Question: Do plants produce bigger flowers if they are fertilized? Hypothesis: How would you answer this question? Write a hypothesis. Remember do not start it with, I think...

Scientific Method If plants are fertilized weekly, then they will produce bigger flowers than those receiving no fertilizer. If plants are fertilized weekly, then they will produce smaller flowers than those receiving no fertilizer. If plants are fertilized weekly, then there will be no difference in the size of the flower compared to those receiving no fertilizer. Many different hypotheses can be written.

Scientific Method Now that a hypothesis has been written, what is the next step? Experiment What are the important features of an experimental design?

Scientific Method Procedures must be clear. Remember, the experiment must be repeatable. Everything in the experiment must be the same, except for the one variable that is being tested. This is called the independent variable. The sample size should be large! This will reduce error.

Scientific Method Design an experiment to test the following hypothesis: If plants are fertilized weekly, then they will produce bigger flowers than those receiving no fertilizer. Analysis: Big picture (Experiment) What are the parts?

Scientific Method Variables are factors that can effect the outcome of an experiment. What are the factors or variables that could effect the outcome of this experiment?

How will we make sure that they do not influence the experiment? Do we want all of these variables to have an impact on the experiment?

Scientific Method Two groups will be set up. The experimental group and a control group. All variables will remain the same in both groups, except for the independent variable: fertilizer. The control group is used for comparison, to find out if the experimental variable has an effect on the experiment.

Experimental Design 200 week old petunia plants (same species) Use the same containers, soil mixture, water amount, same green house location (temperature, humidity, light) 100 plants will receive 2 tablespoons of miracle grow each week (Experimental Group), while the remaining 100 will not (Control Group).

Scientific Method So, the independent variable is fertilizer. What is the dependent variable? What outcome is dependent on the experiment? In other words, what data is being collected? Flower size

Scientific Method What comes next? Remember, there are two types of observations: Qualitative and Quantitative Collecting Data and making Observations. Qualitative: qualities such as appearance, smell, texture, color Quantitative: quantity such as number, amount, and size

Scientific Method The observations made will concentrate on the size of the flower. What observations will be the focus of this experiment?

Scientific Method What is the next step in the scientific method? Conclusion: Based not on your opinion, but on the results of the experiment. What if your results support your hypothesis? What comes next? The experiment must be repeated to be verified. A theory is a hypothesis that has been accepted.

Scientific Method What happens if the results do not support the hypothesis? The experiment may be repeated, or the hypothesis may be altered and then the experiment repeated.

Review Question Hypothesis If….then Experiment Data Observations Interpretations Conclusion (CLE) Independent Variable Dependent Variable Experimental Group Control Group

Scientific Method