Unit 1c: Scientific Method & Inquiry

The Methods Biologists Use

The common steps that biologists and other scientists use to gather information and answer questions are collectively known as scientific process. Scientific methods usually begin with scientists identifying a problem

to solve by observing the world around them. The scientific process is the only scientific way accepted to back up

a theory or idea. This is the method on which all research projects should be based. The Scientific is used by researchers to support or disprove a theory.

The knowledge obtained when scientists answer one question often generates other questions or proves useful in solving other problems.

We shall take a closer look at these steps and the terminology you will need to understand before you start a science project.

1.2How Scientists Work

1.2How Scientists Work

Observing and Hypothesizing

Scientific methods usually begin with scientists identifying a problem to solve by observing the world around them.

1. Problem/Question: Develop a question or problem that can be solved through experimentation.

2. Observation/Research: Make observations and research your topic of interest.

Do you remember the next step?

3. A Hypothesis is an explanation for a question or a problem that can be formally tested. Hypothesizing is one of the methods most frequently used by

scientists. A hypothesis is not a random guess.

The Methods Biologists Use

Eventually, the scientist may test a hypothesis by conducting an experiment.

The results of the experiment will help the scientist draw a conclusion about whether or not the hypothesis is correct.

1.2How Scientists Work

Experimenting

4. To a scientist, an experiment is aninvestigation that tests a hypothesis by the process of collecting information under controlled conditions.

Some experiments involve two groups: the control group and the experimental group. The control is the group in which all conditions are kept the same. The experimental group is the test group, in which all conditions are kept

the same except for the single condition being tested. The constants in an experiment are all the factors that the

experimenter attempts to keep the same. Trials refer to replicate groups that are exposed to the same

conditions in an experiment.

1.2How Scientists Work

Designing an Experiment

In a controlled experiment, only one condition is changed at a time. The condition in an experiment that is changed is the independent

variable, because it is the only variable that affects the outcome of the experiment.

While changing the independent variable, the scientist observes or measures a second condition that results from the change. This condition is the dependent variable, because any changes in it

depend on changes made to the independent variable.

1.2How Scientists Work

What are Variables?

The independent, or manipulated variable, is a factor that’s intentionally varied by the experimenter.

The dependent, or responding variable, is the factor that may change as a result of changes made in the independent variable.

1.2How Scientists Work

Data Gathering

5. Collect and Analyze Results: Modify the procedure if needed.

Confirm the results by retesting. Include tables, graphs, and

photographs. Information obtained from

investigations is called data. Often, data are in numerical

form. Numerical data may be

measurements of time, temperature, length, mass, area, volume, or other factors. Numerical data may also be counts.

Sometimes data are expressed in verbal form, using words to describe observations made during an investigation.

1.2How Scientists Work

Thinking About What Happened

6. After careful review of the results, the scientist must come to a Conclusion: a statement that accepts or rejects the hypothesis. Make recommendations for further study and possible

improvements to the procedure. Was the hypothesis supported by the data? Was it not supported? Are more data needed?

7. Communicate the Results: Be prepared to present the research/project. Expect questions.

1.2How Scientists Work

Verifying Results

7. Communicate the Results: Be prepared to present the research/project. Expect questions.

Results and conclusions of investigations are reported in scientific journals, where they are available for examination by other scientists. After results of an investigation have been published,

other scientists can try to verify the results by repeating the procedure.

When a hypothesis is supported by data from additional investigations, it is considered valid and is generally accepted by the scientific community.

1.2How Scientists Work

Theories and Laws

In science, a hypothesis that is supported by many separate observations and investigations, usually over a long period of time, becomes a theory.

A theory is an explanation of a natural phenomenon that is supported by a large body of scientific evidence obtained from many different investigations and observations. In addition to theories, scientists also recognize certain facts of

nature, called laws or principles, that are generally known to be true.

1.2How Scientists Work

TAKS Review 1

As temperature drops to the dew point, clouds form in the atmosphere, and dew forms on ground surfaces. A scientist proposes that adding more water molecules to the atmosphere will change the dew point. This proposal is -- an invalid observation c. an invalid problem b. a valid hypothesis d. a valid conclusion

Question 1

A scientist conducts an experiment to test the effect of light on plant growth. In each experiment, three plants of the same variety are each given 10 mL of water. One plant is exposed to full sunlight for 8 hours, one is exposed to full sunlight for 4 hours, and one plant is kept in a dark room. Plant height is measured after two weeks. What is the independent variable in this experiment?

What is the independent variable in this experiment? A. soil volume B. amount of sunlight C. plant height D. amount of water

1.2How Scientists Work

Question 2

Which of the following is the group in an experiment in which all conditions are kept the same? A. standard B. independent variable C. experimental D. control

1.2How Scientists Work

TAKS Review 2

The following boxes represent a field. Which pattern for collecting 10 samples would provide the best data for identifying the types of plants in a field?

a. c.

b. d.

TAKS Review 3

An engineer has created a new engine for race cars. It is necessary to know which fuel mixture will allow the engine to run at its peak performance. Which experimental design is best for this investigation?

a. Use one fuel mixture on the engine and measure its performance b. Use one fuel mixture on many types of engines and measure their performance

c. Use various fuel mixtures on the engine and measure its performance d. Use various fuel mixtures on many types of engines and measure their

performance