Biology- The Scientific Method

Learning Goals: SWBAT

Formulate predictions, questions and hypotheses based on observations.

Evaluate appropriate resources. Design and conduct controlled

experiments. Evaluate experimental design, analyze

data to explain results and propose further investigations.

Communicate results

Curriculum-Framing Questions

Why is the scientific method process used by scientists?

What are the steps of the scientific method?

What Science Is and Is Not?

Science is an organized way of using evidence to learn about the natural world.

The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions.

What does this mean? Scientists deal

only with the natural world; they collect and organize information in a careful, orderly way, looking for patterns and connections between events; and they propose explanations that can be tested by examining evidence.

What Science is and is not Activity

In groups of two, propose an explanation for why it rains, w/o including any scientific thinking in your explanation.

A member of the group will present its explanation to the class.

What Science is and is not Activity Cont’d

Suppose someone does not believe your explanation, could you supply evidence to support your explanation? Why not?

Thinking Like a Scientist

Seeks to answer questions about the natural world.

Use the Scientific Method to test hypothesis.

Provides accurate, reliable answers to questions/problems.

The Scientific Method: 1. Making Observations (think of a

question) 2. Formulate a Hypothesis 3. Design your Experiment: Variables 4. Conduct the Experiment 5. Analyze Data Using Graphics 6. Drawing conclusions 7. Communicating results

Observations

The process of gathering information about events or processes in a careful orderly way.

Using our senses to make observations of the natural world.

Observations The information

gathered from observations is called data.

There are two main categories of data: Quantitative and Qualitative.

Quantitative data are expressed as numbers, obtained by counting or measuring.

Qualitative data are descriptive and involve characteristics that can’t usually be counted. Ex. “the scar appears old” and “the animal seems healthy and alert.”

Quantitative or Qualitative?

Quantitative or Qualitative?

Scientists use data to make

inferences. Inference is a logical

interpretation based on prior knowledge or experience.

Could it be a logical conclusion based on prior knowledge and experience?

What is the inference? What is the observation?

Hypothesis A hypothesis is a proposed

scientific explanation for a set of observations.

Scientists generate hypotheses using prior knowledge, or what they already know; logical inference; and informed, creative imagination.

Hypothesis Cont’d

Scientific hypotheses must be proposed in a way that enables them to be tested.

Some hypotheses would be ruled out. Others might be supported and eventually confirmed.

Sick from McDonald’s?

Several students get sick after eating a Big Mac at McDonald’s.

Formulate a competing hypothesis.

Experimentation Designing an

activity/experiment to test a hypothesis under controlled conditions. A good experiment tests only one variable at a time and a control is used.

A good experiment can be replicated by other scientists and the same results can be obtained.

Data Analysis

Keeping careful and accurate records to see if data supports hypothesis.

Mathematics and statistics are used to determine whether the observations or experimental results are meaningful or just the result of chance or coincidence.

Data Analysis(Evidence) Cont’d

Researchers working on complex questions often collaborate in teams analyzing, reviewing and critiquing each other’s data and hypotheses.

This helps ensure that the conclusions are valid (must rely on reliable data).

Estimated number of adults & Children living with HIV in 2007.

Using Graphics & Sharing Info

Organizing data into graphic illustrations helps scientists analyze the data and explain it clearly to others.

Tables are a good way to summarize data.

Leading Causes of Death Among Adolescents 15-19 Yrs by Country, AZ 2007

Maricopa Pima Pinal Total

Accident (unintentional injury) 65 29 12 106

Motor vehicle accident 48 16 10 74

Accidental drowning and submersion 0 1 0 1

Accidental discharge of firearms 0 1 0 1

Accidental poisoning 16 11 2 29

Assault (homicide) 45 7 1 53

By discharge of firearms 37 6 0 43

By other means 8 1 1 10

Intentional self-harm (suicide) 25 4 0 29

By discharge of firearms 13 1 0 14

By other means 12 3 0 15

Malignant neoplasms 9 4 1 14

Diseases of heart 5 1 0 6

Congenital malformations 1 2 0 3

Diabetes 1 1 0 2

Asthma 2 0 0 2

Influenza and pneumonia 2 0 0 2

Total, all causes 189 52 15 256

Graphs are used to convey comparisons or trends. 2002 Department of Defense, Survey of Health Related Behaviors Among Military Personnel

Pie charts show % w/the entire circle-(Shows concentration ratio of the major ions in

water)

Communicating Results

Publishing the results. A scientific article must tell the reader

what the question to be answered is, why the question is important or relevant, background information, a precise description of how the work was done, the data that were collected, and the scientist’s evaluation of what the data mean.