The Scientific Method

• Solving a problem by answering a question

• The way in which scientific knowledge is gathered

• Whatever the study, all scientist use specific methods to gather knowledge about an observation

• Scientists follow an orderly systematic approach called the scientific method…it is a way of answering questions about the world we live in

Steps of the Scientific Method

• Consists of a series of steps that may differ slightly

• First there is an observation…Why?…I wonder…What the @%$# is that? Curiosity leads to observations, observations lead to questions!!!

• Observations are undisputable

• Inferences are based on assumptions

Observation

• An observation typically employs one or more of the five senses to perceive objects or events that is undisputable

• Most observations are direct, such as observing an event, however some observations are indirect like electricity

• Observations involve qualitative and quantitative data

• Qualitative observations/data deal with descriptions, words that describe

• Quantitative observations/data deal with numbers…usually a measurement

• Information from an observation must then be organized and used state a problem

Variables• Before an experiment it is

necessary to identify the variables, or the parts of an experiment that change or can be changed…variable = vary = things that change in the experiment

• The independent (experimental) variable is the variable intentionally changed by the experimenter…The independent variable is what you actively change in the experiment to observe for effect

• There can be only one IV!• The dependent variable is the

variable that might change as a result of the independent variable. It depends on the change of the independent variable and can be measured or observed…it responds to the IV

• The independent variable is the cause, the dependent is the effect

PROBLEM• Information from an

observation and variables must then be organized and used to state your PROBLEM

• A good problem is testable…it has variables that can be measured and changed!

• Problem Format: “What is the effect of the IV on the DV?”

• The question in the scientific method is also known as the purpose, question, or statement of problem (SOP)…they all have the same meaning!

Constants & Controls

• Controlled Variables are variables that are not changed and kept the same…used to compare

• They are also known as CONSTANTS, and are NOT the same as a CONTROL GROUP…Ask yourself what should not be allowed to change

• The control group is exposed to all steps of an experiment except the one being tested (the IV)…use of a control group gives greater validity…used for comparison

• Constants & Controls are needed to eliminate alternate explanations of experimental results

• Not all experiments will have a control, but all should have more than one constant!

Hypothesis

• You should have some background knowledge on the topic before you attempt a hypothesis

• Think!! Thinking leads to your own explanations about an observation…this is called the hypothesis…it is a statement that can be tested; based on observations, research, and prior knowledge of a problem. A prediction that involves the following parts:

• If (IV), then (DV), because... This should be a complete sentence!

• It includes the independent and dependent variables

• A hypothesis predicts an answer to the question and can be tested!!

• Hypothesis may be supported by evidence but can never be proven true beyond all doubt…there can be new data at any time!!

Hypothesis (Cont.)

• Developing a hypothesis involves inductive or deductive reasoning

• Inductive reasoning goes from the specific to the general. Deductive reasoning goes from the general to the specific.

• Examples…All turtles have shells. The animal I have captured is a turtle…I conclude that the animal in my bag has a shell…this is deductive reasoning

• Inductive reasoning is assuming that if something happens many times it will happen in all instances…All sheep that I've seen are white; All sheep must be white

Experimenting

• A hypothesis is tested by performing an experiment– Most experiments are

controlled. The step by step numbered list of procedures must be followed in order for someone else to correctly repeat the experiment

• During the experiment the collecting and analyzing qualitative and quantitative datadata or information gathered during the experiment…– Quantitative data is organized

into tables and graphs• After an experiment is

completed, data is examined and interpreted and a conclusion is made using the same type of reasoning applied in making the hypothesis– Conclusions will support or

reject the hypotheses, interpret the graph, relate the experiment to the background information, identify errors, and ask new questions.

DataTitle: DV vs. IV

• Qualitative data is based on observations in the experiment that are not measured. They should be numbered.

• Quantitative data should be organized in a table

IV

(Include units)

Level 1 Level 2 Level 3

DV

(Include Units)

Trial 1

Trial 2

Trial 3

Average

Graphing Data - Axis of a Graph:

• X-axis (horizontal axis)Horizontal

means: ????• Y-axis (vertical axis)

Vertical means: ???REMEMBER DRY MIXMake sure you title

your graph and it includes your variables!!!

Axis & Variables• Only graph the

averages in your data!! Not every trial

• If the data has a positive relationship, both they IV and DV do the same thing

• If the data has a negative relationship, the IV and DV do the opposite

The Scientific Method

• After a number of experiments, scientists may create a natural law

• Natural laws describe how nature behaves in a particular way but not usually why…will sometimes have a mathematical relationship and are factual under certain conditions…a generalization that describes recurring facts or events in nature; accepted as true throughout the scientific community

• Theories will explain why nature behaves in a particular way…an accepted explanation of some aspect of the natural world

• Theories are supported by many hypothesis experiments, tentatively answer all questions, and may predict the results of future questions/experiments

• Theories can be wrong!! Knowledge gained is tentative, or open to revision

• According to Stephen Hawking in A Brief History of Time, "a theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model which contains only a few arbitrary elements, and it must make definite predictions about the results of future observations". He goes on to state, "any physical theory is always provisional, in the sense that it is only a hypothesis; you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation which disagrees with the predictions of the theory". The "unprovable but falsifiable" nature of theories is a consequence of the necessity of using inductive logic.

Theories