The Scientific Method

Vocabulary hypothesis independent variable dependent variable control Methods of Scientists Get your vocabulary sheet out! Vocabulary hypothesis independent variable dependent variable control Le Système International d’Unités (SI) -Theory

The Nature of Scientific Investigations Methods of Scientists The Nature of Scientific Investigations A scientific method is a planned, organized approach to solving a problem. Once the problem is defined and research is complete, a hypothesis, or suggested explanation for an observation, is made. Ex. IF I put 10 pounds of fertilizer on the grass, THEN the grass will grow better.

The Nature of Scientific Investigations Experimentation A hypothesis is tested by conducting an experiment, which is an organized procedure that involves making measurements and observations. A good scientific experiment tests only one variable, or changeable factor, at a time. The independent variable in an experiment is the factor that is manipulated by the experimenter. A dependent variable is a factor that can change if the independent variable is changed. A control is used to show that the results of an experiment are a result of the condition being tested.

What is a Variable? A variable is any factor, trait, or condition that can exist in differing amounts or types. Ex. Hypothesis: Fish live longer in COLD water. What are some things (variables) we could change to test this?

Independent Variable Something that can be manipulated by the experimenter. Ex. Maybe instead of 10 pounds of fertilizer, I’ll use 50 pounds.

Dependent Variable The result that is influenced by the independent variable. Ex. WOW, with 50 pounds of fertilizer, the grass grew EVEN more!

The Control The control in an experiment shows how the actual results differ from the treatment. The control doesn’t change.

The Nature of Scientific Investigations What is the independent variable in this picture?

Bart believes that mice exposed to microwaves will become extra strong(maybe he's been reading too much Radioactive Man). He decides to perform this experiment by placing 10 mice in a microwavefor 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. He found that 8 out of 10 microwaved mice were able to push the block away. 7 out of 10 of the non-microwaved mice were able to do the same. What is being tested? What is the control group? What is the experimental group? What should Bart's conclusion be?

Krusty was told that a certain itching powder was the newest and best thing on the market; it even claims to cause 50% longer lasting itches. Interested in this product, he buys the itching powder and compares it to his usual product. One test subject (A) is sprinkled with the original itching powder, and another test subject (B) was sprinkled with the Experimental itching powder. Subject A reported having itches for 30 minutes. Subject B reported to have itches for 45 minutes. What is being tested? What is the control group? What is the experimental group? What should Krusty's conclusion be?

Measurement Time  ??? Seconds Methods of Scientists Most scientific studies and experiments use a standard system of metric units called Le Système International d’Unités, or SI for short. SI is a modern version of the metric system based on a decimal system that uses the number 10 as the base unit. Time  ??? Seconds Length  not feet or inches but…Meters or Centimeters Mass  ??? Kilogram Area  ??? cm2 Temperature  Celsius

Communication Scientists must share the results of their studies with other scientists (peers) Publish findings in journals Present their findings at scientific meetings Scientists must be unbiased Should not tamper with their data Only publish & report tested & proven ideas We will use Google Documents!

Theories A theory may be formed after many related hypotheses have been tested and supported with experimental evidence, but it is not Law. A broad and comprehensive statement of what is thought to be true Supported by considerable evidence Ties together related hypotheses Theory of Plate Tectonics Theory of Evolution Theory of Natural Selection

Laws A Statement of fact that concisely explains an action or group of actions e.g. Law of Gravity Accepted to be true Universal May be expressed as a math equation e.g. E=mc2 What does “C” stand for?