Scientific Method

What is the scientific method….. ? The scientific method is a ______ for answering questions. process

SCIENTIFIC METHOD A series of steps that scientists use to answer questions and solve problems. Is not a rigid procedure. Scientists may use all of the steps or just some of the steps. They may even repeat some of the steps. The goal of the scientific method is to come up with reliable answers and solutions to questions.

Steps in the Scientific Method Observation Define a problem Hypothesis Experiment Data Collection/analysis Conclusion Retest

Observations Gathered through your senses A scientist notices something in their natural world

Observations An example of an observation might be noticing that many salamanders near a pond have curved, not straight, tails

Define a problem The scientific method starts with observations that lead to questions…defining a problem. (5 Senses) How, What, When, Where, why? Initial observations and inferences.

Hypothesis A suggested solution to the problem. Must be testable Sometimes written as If…Then… statements Predicts an outcome ***A hypothesis is a testable explanation for an answer to an observation, question or problem.

Hypothesis An example of a hypothesis might be that the salamanders have curved tails due to a pollutant in the moist soil where they live.

A valid hypothesis has three characteristics 1. Testable 2. Unbiased 3. Repeatable If a hypothesis satisfies these criteria it can be accepted as a Scientific Theory*

A procedure to test the hypothesis. Experiment A procedure to test the hypothesis.

Variable – factor in the experiment that is being tested

Experiment A good or “valid” experiment will only have ONE variable! (meaning only one thing is changed at a time)

Controls and Variables

Scientific Experiments Follow Rules An experimenter changes one factor (Independent variable) and observes or measures what happens (dependent variable).

The Control Variable The experimenter makes a special effort to keep other factors constant so that they will not effect the outcome. Those factors are called control variables.

What is the Purpose of a Control? Controls are NOT being tested Controls are used for COMPARISON

Other Variables The factor that is changed is known as the independent variable. It is graphed on the x axis. (I Do) The factor that is measured or observed is called the dependent variable. It is graphed on the y axis. (Data)

Example of Controls & Variables For example, suppose you want to figure out the fastest route to walk home from school. You will try several different routes and time how long it takes you to get home by each one. Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

What are the Variables in Your Experiment? Varying the route is the independent variable The time it takes is the dependent variable Keeping the same walker throughout makes the walker a control variable.

One more thing… it is best to make several trials with each independent variable.

Valid Experiments

Remember: To be a Valid Experiment: Two groups are required --- the control & experimental groups There should be only one independent variable

Data Results of the experiment May be quantitative (numbers/measurements) or qualitative (descriptions) Analysis- Data is evaluated.

Data Must be organized Can be organized into charts, tables, or graphs

Conclusion The answer to the hypothesis based on the data obtained from the experiment

In order to verify the results, experiments must be retested.

Review

Solving a Problem 1)Identify a Problem 2) State Observations about the problem 3) Form a Hypothesis about the problem (if…then…) 4) Design an Experiment to test the hypothesis 5) Collect Data 6) Form a Conclusion 7) Retest

Scientific Theory vs. Law What is the difference?

Scientific Theory vs. Law Explanation for an observation that is confirmed by a large amount of evidence or tests (experiments). Example: Germ theory of disease - Infectious diseases result from the action of microorganisms. LAW A statement of a scientific principle that appears to be without exception at the time it is made, and always works the same way under the same conditions; A scientific rule. Newton's First Law of Motion (Law of Inertia) - every object either remains at rest or in continuous motion with constant speed unless acted upon by an outside force. Treponema pallidum - ♪ (Trep-o-neemah pal-lid-um)

So, what's the difference? A SCIENTIFIC THEORY - are typically non-mathematical. A SCIENTIFIC LAW - are often mathematically defined Looking at things this way helps to explain, in part, why physics and chemistry have lots of "laws" whereas biology has few laws (and more theories). In biology, it is very difficult to describe all the complexities of life with "simple" (relatively speaking!) mathematical terms.

Scientific Theory vs Law How are they the same? both are based on tested hypotheses both are supported by a large body of empirical data both help unify a particular field both are widely accepted by the vast majority (if not all) scientists within a discipline. both scientific laws and scientific theories are true based on what we know today – but they can be changed with new information.

What is the study of living things? Name the characteristics of living things and define three of them. Extra credit: What does DNA stand for… spell it correctly.

Table of contents 1 8/20 intro bell ringer, SM, metric 2 8/22 What is living 3. 8/23 Learning Targets 4. 8/23 Characteristics of organisms (circles) 5. 8/28 What is Biology 6. 8/29 Scientific Method 7. 8/23 Safety (I have until next week) 8. 8/30 Quiz 1… characteristics 9. 8/30 Prefix list and worksheet