The Scientific Method

Objectives What is the scientific method? What are the steps of the scientific method? What is a theory? What is a scientific law?

The Scientific Method A process or series of steps that are utilized to answer questions about the world around us. How scientists come up with new theories and new ideas.

The Steps Include Observation Hypothesis Experiment Results and Data Conclusion

Observation typically information obtained through the five senses then a why or how question is asked about the information.

Two Types of Observation Qualitative – a type of observation that does not involve numbers such as the water is blue. Quantitative – a type of observation that involves numbers such as there are four squares and two circles. Qualitative Quantitative

Observations: Fact or Opinion A good question for a science experiment is one that you can answer based on facts. Fact – verifiable truths –Fact: Photosynthesis takes place in green plants –Question: What factors increase the rate of photosynthesis? Opinion – beliefs based on personal experiences that can not be proven true –Opinion: Science is more interesting than Literature –Question: Which is more interesting, science or literature? »Practice Using “Fact and Opinion” Handout

Hypothesis A prediction based on prior knowledge (observations made and questions asked) An educated guess based on facts A statement that is testable or can be proven to be right or wrong. Is it a question or a statement?

Forming a Hypothesis Ask yourself the following questions: –What do I already know? –What do I think the answer is? –What do I think will happen? Example: I know that plants are green. I think (hypothesize) that plants will grow at a faster rate in green light.

Experiment Is a procedure performed to test the hypothesis. It is usually presented in a step by step format. What will happen first, second, third, and etc.? What materials are needed to perform the experiment?

Experimental Components Control – something that does not receive experimental treatment and the conditions are viewed as normal. Experimental results are compared to the control to verify results. –Question: Do plants grow at a faster rate in some colors of light? –Hypothesis: I think plants grow at a faster rate in green light. –Control: A separate plant will receive all colors of light (white light).

Experimental Components Experimental Group – the tested group that has two variables: –Independent variable: the piece of the experiment that is worked with during the experiment to obtain results Ex) the number of days –Dependent variable: the piece of the experiment that changes and is being measured Ex) the height of each plant after so many days

Experimental Components Take notes during experiment: -data – the information that describes what is happening during the experiment -Charts and Tables – organizers used to keep data in the proper category

Results and Data Each experiment yields some results and data This information must be presented in an organized manner such as a chart, table, diagram, or graph. This information will be used to prove or disprove your hypothesis.

Results and Data Results can sometimes be displayed as a graph: –Line graph – shows how variables in an experiment change over time. –Bar graph – shows only the end result in specific categories.

Conclusion Is a summary (paragraph) of the events of the experiment. –Based on analyzing the data and notes taken during procedure.

Questions to answer in summary: –What was the question to be answered? –What was your hypothesis. –Did the results prove your hypothesis correct? –What did the results show? –Why do you think the experiment turned out the way it did? –Was the test valid or fair? –What went wrong in your experiment? –How could the procedure be improved to better test your hypothesis? –Is the experiment reproducible by others? Why? –Do you think others will have the same results? Why? –What is at least one question that the results lead you to ask? –What is your new hypothesis, if applicable?

Note: Unfortunately, real scientific problems do not end with nice, neat conclusions. The hypothesis/experiment cycle continues until there are many MANY experimental results that support a hypothesis or set of hypotheses. Then a theory can be formed.

The Scientific Method 1.Observe an event. 2.Develop a hypothesis. 3.Create and perform an experiment. 4.Analyze the results. 5.Make a conclusion 6.Revise the hypothesis and Repeat as needed. 7.A successful hypothesis becomes a Scientific Theory. Investigation Cycle

Theory Is an explanation of why repeated experiments give certain results. Theories can only be disproven never proven Theories can give a scientist the ability to predict the outcome of an experiment. Can sometimes be called models. Theories can be revised as new information can become available. Some examples of theories include The Big Bang Theory, The theory of Evolution, etc.

Scientific Law a summary of observations or experimental results of natural occurrences are made without trying to explain why they happen In this course we will study and apply many scientific laws such as the Law of the Conservation of Mass Many scientific laws are expressed in mathematical form