Theories vs. Laws blob:https%3A//www.youtube.com/81ae1858-99b0-415b-8976-05b3541a7a32 Laws describe specific relationships in nature. It DOES NOT attempt to explain them. Example: Law of conservation of mass. (matter is not created nor destroyed) Theories are well supported explanations of relationships in nature. Example: the cell theory, the sliding filament theory for muscle contraction, etc. These come from extensive repeated testing/experiments. Theories DO NOT become laws.

The Scientific Method Make observations Formulate a hypothesis based on research Devise a testable prediction Conduct a critical experiment Draw conclusions, make revisions Communicate your results

Hypothesis Null Hypothesis Proposed explanation for observed phenomena Echinacea reduces the duration and severity of the common cold. Null Hypothesis Hypothesis that states a lack of relationship between two factors Easier to disprove Echinacea has no impact on the duration or severity of the symptoms of the common cold.

Make it into a testable question/prediction Common way is to use the If/Then format If Echinacea reduces the duration and severity of the symptoms of the common cold, then individuals should be sick less frequently than those not taking it, and when they do get sick, their illness should not last as long.

On to the experiment! Treatment – the experimental condition applied to the research subjects. (the Echinacea) Treatment group – your test subjects that are exposed to your treatment. (the ones getting the Echinacea) Control Group – Group of subjects that are treated the same as the treatment group, EXCEPT for receiving the treatment. Variables – Characteristics of an experiment that are subject to change. (the amount of Echinacea given, or how frequently it is taken, etc.)

Accounting for unintended effects The placebo effect – participants feeling benefits from any treatment even if it does not do anything. Blind experimental design – This design does not allow the participant to know if they are getting the actual treatment or just a fake treatment (placebo). Double blind – both the researcher and the participant do not know which people are getting the treatment and which are getting the placebo. Randomized – participants are randomly selected to be in the experimental/control groups.