Scientific Method Vocabulary Observation Hypothesis Prediction Experiment Variable Experimental group Control group Data Correlation Statistics Mean Distribution Probability Sample

Scientific Method Mr. Washington Environmental Science Lehigh Senior High

The Scientific Method Science is ultimately based on observation and observations lead to questions which leads to experiments that answers the question.

Hypothesis A testable statement that can be shown to be true or false by experimenting or observing is call a hypothesis.

Prediction Once a hypothesis is formed, then a prediction can be made, a prediction is an expected outcome.

Experimentation Hypothesis are tested by experimentation. Experimentation is a planned procedure designed to test a hypothesis.

Experiments & Groups In order, to conduct an experiment correctly you will need 2 groups; a control group and an experimental group. Control – receives no treatment, what we are comparing Experimental-receives some kind of treatment or condition.

Variables There are 2 types of variables in an experiment; independent and dependent. Independent- the factor that changes what you do to the experimental group. Dependent – what happens as a result of the treatment, what we are measuring.

Data All data (results) should be presented in a neat fashion, graphs and tables are the best choice.

Conclusion Based on the data collected we can determine whether the hypothesis was supported or not. BEWARE!! The word prove is usually not used because there are no absolutes in science. In science, every conclusion is only “true to the best of our knowledge” since science is subject to change when new evidence is found.

What is a theory? A theory is an explanation of natural events that is based on a large number of observations. Theories explain what we observe.

Science & Theories Data → data from an experiment can lead to a theory Theory → a hypothesis that can withstand repeated testing can become part of a theory.

Scientific Law Certain facts consistently remain the same in Science; this is called a law. A scientific law is a description (not explanation) or mathematical expression that reliably describes the behavior of the natural world. ex: Law of Conservation of Mass

Hypothesis vs. Theory vs. Law A hypothesis predicts an event. A theory explains it. A law describes it.

Correlations & Hard Questions Some questions scientists can not answer by conducting experiments. ex: Does smoking cause lung cancer in humans? This experiment can cause harm and is considered unethical. Another question that can not be answered is what is the average temperature on Earth 60 mya? Answering this question is impossible because we are 60 mya too late.

The Correlation Method If scientists are unable to conduct an experiment due to unethical reasons or a question is impossible to answer, scientist test predictions by examining correlations or reliable associations between 2 or more events. Examples: High Drought Index vs. increases in brush fires Calcium intake vs. Bone fractures

Not Proven Correlations can be useful for scientists, they do not necessary prove a cause and effect relationship between 2 variables. Scientists become more confident in their findings if they find the same correlation in a different place and can eliminate other possible explanations

Statistics and Models Statistics is the collection and classification of data that is in numeric form. Scientists use statistics several different ways in science, some examples are average rainfall in a given month/year, or mean life expectance of males/females.

Average ↔ Mean In statistics, a mean is the # obtained by adding up the data for a given characteristic and dividing the sum by the # of individuals. This is also known as an average.

Distribution A distribution is the relative arrangement of the members of a statistical population and is usually shown in a graph.

Probability The likelihood that something will happen in the future is called probability. It represents a mathematical ratio of a number of times an outcome is likely to occur to the number of possible outcomes of an event.

Sample In science, a proper sample size is best to gather accurate results. Sample is the group of individuals or events selected to represent the population.

Models Models are used to represent objects or systems. There are several different types: physical, graphic, conceptual & mathematical. Ex: DNA

Conceptual Model Conceptual models are verbal or graphical explanation of how a system works or is organized. Ex: flow charts

Mathematical Models Mathematical models are 1 or more equations that represents the way a system or process works. Ex: D=m/v Area= l x w H 2 + O 2 → H 2 O

Graphs & Charts Graphs and charts are a good way to present results for an experiment. There are several different types: line graph, bar graph, pie charts, flow charts and Venn Diagrams are just to name a few.

Bar Graphs Bar graphs are used when measuring frequency or comparing data, also know as a histogram.

Line Graphs Line graphs help present the results in an experiment, it shows how a controlled variable affects another variable. Line graphs are good for showing the relationship between these 2 variables

Pie Charts Pie charts are an easy way to visualize how many parts make up the whole. Frequently, pie charts are made up from percentage data and the total equals a100%

Flow Charts Flow charts are helpful in presenting sequence of events or a cause and effect relationships