1 Copyright©2000 by Houghton Mifflin Company. All rights reserved.

A process of studying natural phenomena that involves making observations, forming laws and theories, and testing theories by experimentation 2 Copyright©2000 by Houghton Mifflin Company. All rights reserved. The Scientific Method

Make Observations Qualitative  Descriptions Quantitative  Measurements Formulate Hypotheses Possible Explanations for Observed Characteristics or Behaviors Perform Experiments Test Hypothesis 3 Copyright©2000 by Houghton Mifflin Company. All rights reserved. The Scientific Method

Evaluate your Proposed Solutions Test your Patterns by using them to Predict What Will Happen Experiments 4 Copyright©2000 by Houghton Mifflin Company. All rights reserved. Solving Problems Using a Scientific Approach

Repeat the process until we get a well-tested explanation Theory  a set of assumptions put forth to explain some aspect of the observed behavior of matter May need to be modified or discarded as new information (observations) becomes known 5 Copyright©2000 by Houghton Mifflin Company. All rights reserved. The Scientific Method

While Experimenting we may Observe the Same Behavior all the time, and therefore be able to Predict this Behavior will Always Occur in the Future Law  a generally observed behavior Without explanation as to why the behavior occurs! 6 Copyright©2000 by Houghton Mifflin Company. All rights reserved. The Scientific Method

Laws predict what will happen Theories explain why something happens Models are an explanation of how phenomenon occur and how events and data are related. Can be visual, verbal, or mathematical 7 Copyright©2000 by Houghton Mifflin Company. All rights reserved. The Difference Between a Theory and a Law

Variable—anything that can change in an experiment Independent/manipulated variable—what scientist alters (only 1 can be changed) Dependent/responding variable—what scientist measures Control—standard for comparison with no ind variable Constant—same in all trials so results can be attributed to the independent variable Inferences—assumption/conclusion based on observations 8 Copyright©2000 by Houghton Mifflin Company. All rights reserved. Experimental Design

After studying about recycling, members of John’s biology class investigated the effect of various recycled products on plant growth. John’s lab group compared the effect of different aged grass compost on bean plants. Since decomposition is necessary for release of nutrients, the group hypothesized that older grass compost would produce taller bean plants. Three flats of bean plants (25 plants/flat) were grown for 5 days. The plants were then fertilized as follows: Flat A: 450g of three-month-old compost; Flat B: 450g of six-month-old compost; and Flat C: 0g of compost. The plants received the same amount of sunlight and water each day. At the end of the 30 days the group recorded the height of the plants (cm). Ind/Manip variable is Dep/Resp variable is Control is Constant is 9 Copyright©2000 by Houghton Mifflin Company. All rights reserved. Example

1. Recently, a high school student reported that he was feeling ill. His symptoms included headaches and nausea. He had attended school, eaten at a restaurant for dinner, and then played basketball. How can the following hypotheses be tested to determine the cause of his problem? Which hypothesis is not testable? His illness was caused by food poisoning at the restaurant. He inhaled certain noxious fumes during chemistry lab that made him sick. He was dehydrated from the basketball game. His illness caused his nausea. 10 Copyright©2000 by Houghton Mifflin Company. All rights reserved. Questions:

2. Write a hypothesis to explain each of the following observations: The static on your AM radio station increases right before it thunders during a thunderstorm. People who smoke cough more than people who don’t smoke. More people carry briefcases in the airport on Tuesdays than on Saturdays. 11 Copyright©2000 by Houghton Mifflin Company. All rights reserved. Questions cont.:

Mini- Lab Non-burning cup You are about to observe an unusual phenomenon, water boiling over a flame in a paper cup. Use your reasoning skills to help you develop a hypothesis as to why this occurs. Procedures: Use tongs to hold a paper cup containing water over the flame of a gas burner. Allow the flame to touch only the bottom of the cup. Hold the cup over the flame until the water boils. 12 Copyright©2000 by Houghton Mifflin Company. All rights reserved. Mini Lab Activity

Possible Hypotheses: __________________________________________ ________________________ 13 Copyright©2000 by Houghton Mifflin Company. All rights reserved. Observations