Scientific Investigation Notes

Common Misconceptions About Scientific Theories and Laws Misconception 1 : Hypotheses are just guesses. Correction: Hypotheses are reasoned and informed explanations.  Misconception 2: Theories are just hunches. Correction: In science, theories are broad explanations. To be accepted, they must be supported by many lines of evidence.  Misconception 3: If evidence supports a hypothesis, it is upgraded to a theory. If the theory then garners even more support, it may be upgraded to a law. Correction: Hypotheses cannot become theories and theories cannot become laws. Hypotheses, theories, and laws are all scientific explanations but they differ in breadth, not in level of support. Theories apply to a broader range of phenomena than do hypotheses. The term law is sometimes used to refer to an idea about how observable phenomena are related. Source: http://undsci.berkeley.edu/article/howscienceworks_19

What is scientific theory What is scientific theory? How are theories different from scientific laws? Scientific Law: observations (facts) ; can often be described mathematically Scientific theory: model or explanation for observations

Scientific Method Observations Question Research Hypothesis to test Materials & Procedure (Experiment Design) Experiment Results (Observations + Data) Analysis Conclusions & Discussion Evalution

Objectives: What is a scientific theory? How is it different from scientific laws? What is an independent variable? What is a dependent variable? What are control/constant variables? What is a control group? How is it different from control/constant variables? How is it different from the experimental group? What is the difference between replicates and trials? What is a statistical “mean”, and why is it calculated when evaluating data? What is standard deviation and why is it calculated it when evaluating data?

What is an independent variable? What is changed by the investigator What is tested in an experiment Presumed to be the cause of something (the dependent variable) A well designed investigation considers only one independent variable, but as many “treatments” of that factor Examples: Age groups, temperatures, locations

What is a dependent variable? The factor that is being observed and measured during the investigation It is the presumed effect of the independent variable “Depends on changes in the independent variable

Control/Constant Variables Factors and conditions that are not changed during an investigation Help to control investigation so that any changes in the dependent variable would be only due to the independent variable Well designed experiments attempt to control as many factors as possible

Example: 1) Identify the IV and DV variables Example: 1) Identify the IV and DV variables. 2) Identify at least 3 controls that would be relevant to this investigation. Younger aged people will be able to complete a jigsaw puzzle faster than people of older ages.

Younger aged people will be able to complete a jigsaw puzzle faster than people of older ages. Independent Variable: Age Dependent Variable: Time (in seconds, minutes, etc.) Control/Constant Variables: Constant: Jigsaw Puzzle The same jigsaw puzzle will be used for all participants. Sleep Only participants that have had a 8-9 hours of sleep will be included in the study. Testing Conditions All participants will be tested in the same room conditions.

What is the experimental group? The participants that are exposed to the independent variable

What is a control group? The participants that are treated just like the experimental group EXCEPT they are not exposed to the independent variable; the group with which the experimental group can be compared

Example: Adding fertilizer to my garden bed will increase the growth rate of my plants. Experimental Group: Bed with added fertilizer Control Group: Bed without fertilizer.

How are replicates different from trials? Replicates are copies Trials are repeats of the entire procedure