http://www.project2061.org/publications/bsl/online/index.php?chapter=1
http://evolution.berkeley.edu/evosite/nature/index.shtml
Vocabulary
anecdotal evidence
A description of an event that is used to make a point.
biogeography
The study of the distribution of living organisms.
ecology
The study of the interactions of organisms with each other and with their environment.
evidence
Something that gives us grounds for knowing of the existence or presence of something else.
life science
The study of living organisms and how they interact with each other and their environment.
population biology
The study of the biodiversity, evolution, and environmental biology of populations of organisms.
science
A way of knowing about the physical world, based on observable evidence, testing predictions, and reasoning.
science theories
Well established and tested explanations of observations; produced through repeated studies, usually performed and confirmed by many individuals.
Points to Consider
Next we are going to discuss the scientific method. You may have heard someone say that you can ruin your eyes if you sit too close to the television set.
Describe how “thinking like a scientist” could help you figure out if this common sense idea is true or false.
Lesson 1.2: The Scientific Method
Lesson Objectives
Consider how the scientific method is one of the most important reasons for how modern science is advancing more rapidly than in the past.
Describe the scientific method as a process.
Explain why the scientific method allows scientists and others to examine the physical world more objectively than other ways of knowing.
Describe the steps involved in the scientific method.
Check Your Understanding
What is science?
What is a scientific theory?
Introduction
The scientific method is an inquiry process used to investigate the physical world using observable evidence and testing. This method allows scientists to "conduct" science in a uniform process. This process allows the information collected to be reproduced by other scientists, and most importantly, this process allows the information to be accepted and trusted.
Observations, Data, Hypotheses, and Experiments
Imagine that you are scientist who wants to know something like, “Why do whales migrate?” or “Why do some people get more colds than others do?” Two hundred years ago you could have come up with theories without necessarily thoroughly testing your ideas. But there were many exceptional scientists who made outstanding contributions. Here is a painting of Michael Faraday in his laboratory in the Royal Institution in England during the 1800s (Figure below). Michael Faraday is best known for his contributions to chemistry, and he probably used some form of the scientific method to answer his questions.
Figure 1.13
Michael Faraday in his laboratory at the Royal Institution during the mid 1800s.
As a modern scientist today, you would use the scientific method, collecting evidence to test your hypothesis and answer your questions. The scientific method presents a general idea of how science is conducted; it is not a strict pattern for doing research. Scientists use many different variations of the scientific method to meet their specific needs. Almost all versions of the scientific method include the following steps, though not always in the same order:
Make observations
Identify a question you would like to answer about the observation
Research: find out what is already known about your observation
Form a hypothesis
Test the hypothesis
Analyze your results
Communicate your results
A hypothesis is a proposed explanation that allows you to make predictions about what ought to happen if the hypothesis is true. If the predictions are accurate, that provides support for the hypothesis. If the predictions are incorrect, that suggests the hypothesis is wrong.
Make Observations
Observe something in which you are interested. Here is an example of a real observation made by students in Minnesota (Figure below). Imagine that you are one of the students who discovered this strange frog.
Figure 1.14
A frog with an extra leg.
Imagine that you are on a field trip to look at pond life. While collecting water samples, you notice a frog with five legs instead of four. As you start to look around, you discover that many of the frogs have extra limbs, extra eyes or no eyes. One frog even has limbs coming out of its mouth. You look at the water and the plants around the pond to see if there is anything else that is obviously unusual like a source of pollution.
Identify a Question That is Based on Your Observations
The next step is to ask a question about these frogs. For example, you may ask why so many frogs are deformed. You may wonder if there is something in their environment causing these defects. You could ask if deformities are caused by such materials as water pollution, pesticides, or something in the soil nearby (Figure below).
Yet, you do not even know if this large number of deformities is “normal” for frogs. What if many of the frogs found in ponds and lakes all over the world have similar deformities? Before you look for causes, you need to find out if the number and kind of deformities is unusual. So besides finding out why the frogs are deformed, you should also ask:
“Is the percentage of deformed frogs in pond A (your pond) greater than the percentage of deformed frogs in other places?”
Figure 1.15
A pond with frogs.
Research Existing Knowledge About the Topic
No matter what you observe, you need to find out what is already known about your topic. For example, is anyone else doing research on deformed frogs? If yes, what did they find out? Do you think that you should repeat their research to see if it can be duplicated? During your research, you might learn something that convinces you to alter your question.
Construct a Hypothesis
A hypothesis is a proposed explanation of an observation. For example, you might hypothesize that a certain pesticide is causing extra legs. If that's true, then you can predict that the water in a pond of healthy non deformed frogs will have lower levels of that pesticide. That's a prediction you can test by measuring pesticide levels in two sets of ponds, those with deformed frogs and those with nothing but healthy frogs. A hypothesis is an explanation that allows you to predict what results you will get in an experiment or survey.
The next step is to state the hypothesis formally. A hypothesis must be "testable."
Example:
After reading about what other scientists have learned about frog deformities, you predict what you will find in your research. You construct a hypothesis that will help you answer your first question.
Any hypothesis needs to be written in a way that it can:
Be tested using evidence.
Be falsified (found false/wrong).
Provide measurable results.
Provide yes or no answers.
For example, the following hypothesis can be tested and provides yes or no answers:
“The percentage of deformed frogs in five ponds that are heavily polluted with a specific chemical X is higher than the percentage of deformed frogs in five ponds without chemical X.”
Test Your Hypothesis
The next step is to count the healthy and deformed frogs and measure the amount of chemical X in all the ponds. This study will test the hypothesis. The hypothesis will be either true or false. Testing a hypothesis is usually done through an experiment.
An example of a hypothesis that is not testable would be: "The frogs are deformed because someone cast a magic spell on them." You cannot make a
ny predictions based on the deformity being caused by magic, so there is no way to test a magic hypothesis or to measure any results of magic. There is no way to prove that it is not magic, so that hypothesis is untestable and therefore not interesting to a scientist.
Analyze Data and Draw a Conclusion
If a hypothesis and experiment are well designed, the experiment will produce measurable results that you can collect and analyze, and then develop a conclusion. The conclusion should tell you if the hypothesis is true or false.
Example:
Your results show that pesticide levels in the two sets of ponds are statistically different, but the number of deformed frogs is almost the same when you average all the ponds together. Your results demonstrate that your hypothesis is either false or the situation is more complicated than you thought. This gives you new information that will help you decide what to do next. Even if the results supported your hypothesis, you would probably ask a new question to try to better understand what is happening to the frogs and why. When you are satisfied that you have accurate information, you share your results with others.
You will probably revise your hypothesis and design additional experiments along the way.
Communicate Results
Scientists communicate their findings in a variety of ways. For example, they may discuss their results with colleagues, talk to small groups of scientists, give talks at large scientific meetings, and write articles for scientific journals. Their findings may also be communicated to journalists.
Example:
You eventually decide that you have strong results to share about frog deformities. You write an article and give talks about your research. Your results could contribute towards solutions.
Drawing Conclusions and Communicating Results
If a hypothesis and experiment are well designed, the results will indicate whether your hypothesis is true or false. If a hypothesis is supported by the results of a study, scientists will often continuing testing the hypothesis in new ways to learn more. If a hypothesis is false, the results may be used to construct and test a new hypothesis.
The next step is to analyze your results and to communicate them to other scientists. Scientific articles include the questions, methods and the conclusions from their research. Other scientists may try to repeat the experiments or change them. Scientists spend much time sharing and discussing their ideas with each other. Different scientists have different kinds of expertise they can use to help each other. When many scientists have independently come to the same conclusions, a scientific theory is developed. A scientific theory is a well-established explanation of an observation. It is generally accepted among the scientific community. Scientific theories are discussed in The Nature of Science Lesson.
Basic and Applied Science
Science can be "basic" or "applied." The goal of basic science is to understand how things work - whether it's why things fall on the floor or the structure of cells. Basic science is the source of most scientific theory and new knowledge. Applied science is using scientific discoveries to solve practical problems or to create new technologies.
Even though basic research is not intended to solve problems directly, basic research always provides the knowledge that applied scientists need to solve problems. For example, medicine and all that is known about how to treat patients is applied science based on basic research (Figure below).
Figure 1.16
A healthy newborn being examined by a doctor.
Lesson Summary
The scientific method is an inquiry process used to investigate the physical world using observable evidence and testing.
A hypothesis is a proposed explanation of an observation; it is used to test an idea.
A theory is a well-established explanation of an observation.
A hypothesis must be written in a way that can be tested, is falsifiable (to be able to prove that something is false), is measurable, and will help answer the original question.
Review Questions
How is a hypothesis different from a theory?
What does a hypothesis need to include?
What does “falsifiable” mean?
List the steps of the Scientific Method?
What is basic research?
What is applied research?
What does a scientist do if their research results conflict with previous theories or popular knowledge?
Is it OK for scientists to change their ideas?
Further Reading / Supplemental Links
William Souder, A Plague of Frogs: The Horrifying True Story. Hyperion Press, 2000.
Vocabulary
applied science
The application of science to practical problems.
basic science
Research whose goal is just to find out how the world works, not to solve an urgent problem. Basic research is the source of most new scientific information and nearly all new theories.
falsifiable
Testable. If a hypothesis generates predictions that can be shown to be true or false by experiment or observation, the hypothesis is "falsifiable" or "testable."
hypothesis
A proposed explanation for something that is testable.
predict
To say what will happen in a given situation. A scientific prediction is different from an everyday prediction, like predicting the weather before it happens. A scientific prediction is related to a specific hypothesis.
scientific method
A careful way of asking and answering questions to learn about the physical world that is based on reason and observable evidence.
scientific theory
A well-established set of explanations that explain a large amount of scientific information.
Points to Consider
Next we consider the tools of the scientist.
How do you think scientific “tools” can help a scientist?
What do you think is one of the more common tools of the life scientist?
Lesson 1.3: Tools of Science
Lesson Objectives
Describe the growing number of tools available to investigate different features of the physical world.
Describe how microscopes have allowed humans to view increasingly small tissues and organisms that were never visible before.
Check Your Understanding
What is the scientific method?
What is an experiment?
Using Microscopes
Microscopes, tools that you may get to use in your class, are some of the most important tools in biology. Figure below Before microscopes were invented in 1595, the smallest things you could see on yourself were the tiny lines in your skin. The magnifying glass, a simple glass lens, was developed about 1200 years ago. A typical magnifying glass may have doubled the size of an image. But microscopes allowed people to see objects as small as individual cells and even large bacteria. Microscopes let people see that all organisms are made of cells. Without microscopes, some of the most important discoveries in science would have been impossible.
Figure 1.17
Basic light microscopes opened up a new world to curious people. 1, ocular lens or eyepiece; 2, objective turret; 3, objective lenses; 4, coarse adjustment knob; 5, fine adjustment knob; 6, object holder or stage; 7, mirror or light (illuminator); 8, diaphragm and condenser.
Microscopes are used to look at things that are too small to be seen by the unaided eye. Microscopy is a technology for studying small objects using microscopes. A microscope that magnifies something two to ten times (indicated by 2X or 10X on the side of the lens) may be enough to dissect a plant or look closely at an insect. Using even more powerful microscopes, scientists can magnify objects to two million times their real size.
Some of the very best early optical microscopes were made four hundred years ago by Antoine van Leeuwenhoek (Figure below), a man who taught himself to make his own microscopes (Figure below). When he looked at a sample of scum from his ow
n teeth, Leeuwenhoek discovered bacteria. In rainwater, he saw tiny protozoa. Imagine his excitement when he looked through the microscope and saw this lively microscopic world. Leeuwenhoek discovered the first one-celled organisms (protists), the first bacteria, and the first sperm. Robert Hooke, an English natural scientist of the same period of history, used a microscope to see and name the first "cells" (Figure below), which he discovered in plants.
Figure 1.18
Antoine van Leeuwenhoek, a Dutch cloth merchant with a passion for microscopy.
Figure 1.19
Drawing of microscopes owned by Antoine van Leeuwenhoek. Bacteria were discovered in 1683 when Antoine Van Leeuwenhoek used a microscope he built to look at the plaque on his own teeth.
Figure 1.20
Robert Hookes early microscope.
Some modern microscopes use light, as Hooke's and van Leeuwenhoek's did, but others may use electron beams or sound waves.
Researchers now use four kinds of microscopes:
Light microscopes allow biologists to see small details of biological specimens. Most of the microscopes used in schools and laboratories are light microscopes. Light microscopes use refractive lenses, typically made of glass or plastic, to focus light either into the eye, a camera, or some other light detector. The most powerful light microscopes can magnify images up to 2,000 times. Light microscopes are not as powerful as other higher tech microscopes but they are much cheaper and anyone can own one and see many amazing things.
CK-12 Life Science Page 2