Chapter 1: Scientific Method and Measurement

Steps: 1.Making observations 2.Formulating a hypothesis 3.Controlled experiment 4.Analyzing results 5.Drawing conclusions and verifying results 6.Considering bias

Observation – the act of noting or perceiving objects or events using the senses Direct observation – things we can see Ex: birds in a rain forest Indirect observation – things that cannot be seen but must be observed based on things we can see Ex: gravity

Hypothesis – a possible explanation that can be tested by observation or experimentation Example: the plant was not growing due to a lack of fertilizer

Data can be qualitative or quantitative Qualitative: Deals with descriptions Can be observed but not measured Color, texture, taste, smell, appearance Ex: oil painting has a musty smell; latte has a frothy appearance; freshman class is friendly

Quantitative Deals with numbers Data which can be measured Length, height, time, distance, speed, ages, volume, weight, cost, humidity, temperature Ex: oil painting cost $300; latte is 12 ounces; freshman class has 210 boys and 195 girls

Experiment – a procedure that is carried out under controlled conditions to test a hypothesis Control group – serves as a standard of comparison because the group receives no experimental treatment Independent variable – the single factor that scientists change in an experiment Ex: water, temperature Dependent variable – factors that may change because of the independent variable Ex: growth of a plant

Which is the dependent variable? Independent variable?

Sometimes it is not possible or ethical to perform an experiment, so researchers look for data connected to their topic Ex: cannot ask people to stop brushing their teeth for years to see if they develop heart disease, so you can research factors that contribute to heart disease

In analyzing your data, you may discover that your hypothesis can be supported, or you may discover that your hypothesis was wrong If you discover your hypothesis was wrong, you may have to revise your hypothesis

Scientists draw conclusions that explain the results of their experiment Scientists verify their results by conducting experiments many times, as well as check with other scientists to see if they have found similar results

Conflicts of interest could arise if a company is performing an experiment that could reflect poorly on a product they sell Ex: tobacco companies might not perform experiments that show cigarettes could cause cancer

Vocabulary: Belief – opinion or conviction that something is true (could become a fact) Fact – truth known by actual experience or evidence (could become a theory) Theory – a system of ideas that explains many related observations and is supported by a large body of evidence acquired through scientific investigation (could become a principle/law) Principle/Law – truths that are valid everywhere in the universe (ex: gravity, conservation of energy, planetary motion)