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 Observation Define a problem Define a problem Hypothesis Hypothesis Experiment Experiment Data Collection/analysis Data Collection/analysis Conclusion Conclusion Retest Retest
Observations Gathered through your senses Gathered through your senses A scientist notices something in their natural world 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 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) The scientific method starts with observations that lead to questions…defining a problem. (5 Senses) How, What, When, Where, why? How, What, When, Where, why? Initial observations and inferences. Initial observations and inferences.
Hypothesis A suggested solution to the problem. A suggested solution to the problem. Must be testable Must be testable Sometimes written as If…Then… statements Sometimes written as If…Then… statements Predicts an outcome Predicts an outcome ***A hypothesis is a testable explanation for an answer to an observation, question or problem. ***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. 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*
Experiment A procedure to test the hypothesis. A procedure to test the hypothesis.
Experiment 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)
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. 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. 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 Varying the route is the independent variable The time it takes is the dependent variable The time it takes is the dependent variable Keeping the same walker throughout makes the walker a control 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.
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 THEORY 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. Example: 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.
1. What is the study of living things? 2. 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