1-1 What Is Science

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

Science is a process, not a “thing.” Explain this statement.

3 Goals of Science

1. Provide explanations for the natural world

2. Use explanations to understand patterns

3. Make useful predictions about natural events

The Scientific MethodThe scientific method is not a simple set of steps

followed by all scientists, all of time.The scientific method just describes a general style

of investigation.

Example: In the 17th century there was a debate over what caused food to spoil.– Spontaneous Generation: living things, like

maggots, could arise from nonliving substances.

– Biogenesis: living things can only come from other living things.

http://www.accessexcellence.org/RC/AB/BC/Spontaneous_Generation.php

1. Observing and Asking Questions

• Observation – involves one or more senses to gather data

It is important to use all of your senses to collect as much data as you can.

Sight isn’t always enough!

1. Observing and Asking QuestionsScience usually begins with observations:– Quantitative – involves numbers, counting or measuring 3 meters

50 kilograms35 degrees Celsius

– Qualitative – involves characteristics that cannot easily be measured or counted, color or texture (describable)

It smells like fresh baked cookiesThis feels coldThis sounds really loud

Inference – a logical interpretation of data based on prior knowledge

We don’t observe an inference. We use observations to create inferences.

Quick practice

Observations:

• I hear people screaming

• I smell cotton candy, popcorn, and hamburgers

• I see a lot of people

Inference = ?

What are some qualitative and quantitative observations you can make of these skulls?How about an inference based upon your observations?

Goal: Make predictions using observations Create an experiment on paper

Warm up: Make a qualitative and quantitative observation from the picture

• Look at these two sets of animal tracks.

• List 3 OBSERVATIONS

• Make an INFERENCE

Make an INFERENCE

Make 3 OBSERVATIONS

Make 3 OBSERVATIONS

Make an INFERENCE

1. Observing and Asking Questions

– Example Observation: Flies frequently land on the meat a few days before maggots appear.

The Observation leads to a question.

– Example Question: Are the maggots produced by flies?

The Scientific Method2. Inferring and Forming a hypothesis

– Hypothesis: A possible explanation for a set of observations.

– Not just an educated guess– Must be a testable statement

Example: The maggots come from the flies not the rotting meat.

The Scientific Method3. Setting up a controlled experiment

Variables: factors that can change.– Independent (manipulated) variable: the variable that

the experimenter changes.– Dependent (responding) variable: changes in response

to the independent variable. Can be measured.

Francesco Redi used this simple experiment to test the hypothesis.

What is the independent variable?

What is the dependent variable?

The Scientific MethodExperiments are usually divided into two groups:– Experimental Group – the independent variable has

been changed.– Control Group – exactly the same as the experimental

group except the independent variable has not been changed. Experiment without the variable.

Why is the control group important for a good experiment?

What is the experimental group?

What is the control group?

Scientific Method5. Drawing Conclusions– Researchers use data as

evidence to determine if the hypothesis needs to be supported or refuted.

– Ex: Maggots only appeared in the flask that was open to flies.

– Do the results support the

When Experiments Are Not Possible

• How do we learn about animal behavior in the wild?Answer: Field studies – watching the animals without disturbing them.

• Some experiments are prevented because of ethical considerations.

• Think of an example.

Stanford Experiment

Elements of a Good Graph

• Scaling and Increments are even

• Neatness and Accuracy counts

• Title (should include I.V./D.V.)

• Labeling of X and Y axis• No squiggle line• Use a ruler

“DRY MIX” D = dependent variableR = responding variableY = graph information on the vertical axis

M = manipulated variableI = independent variableX = graph information on the horizontal axis

http://gator.gatewayk12.org/~smcgrail/myweb/powerpoint/misleading_graphs/here_are_some_examples_of_mislea.htm

1-2 Communicating ResultsPublishing your research in scientific journals allows scientists

to share ideas and to test/evaluate each other’s work.– Scientist, John Needham, reviewed Redi’s experiment

and thought that he could show that bacteria grows through spontaneous generation.

He boiled broth in an open flask to kill all bacteria.

After several days more bacteria grew in the flask.

What is the problem with this experiment?

Communicating Results• Scientist, Lazzaro Spallanzani, reveiwed Needham’s

experiment and hypothesized that the bacteria could have come from the air.– He repeated Needham’s experiment but he sealed the

flasks.– Showed that bacteria did not grow in the broth, and

supported biogenesis.

Scientists did not accept Spallanzani’s conclusions. Why not?

Louis Pasteur • Scientist continued to debate about spontaneous

generation until 1859.• Because scientists published their experiments they

critique and improve on the design.• Louis Pasteur repeated the experiment but this time he

used a flask that would let air in but keep out bacteria.

Did Pasteur’s results support biogenesis or spontaneous generation?

Explain how this process of communicating results improves our understanding?

How a Theory Develops• Theory – a well-tested explanation that ties together

many different observations and hypotheses.– No theory is considered absolute truth because

science is always changing.– Biogenesis is a well tested theory– How is the scientific use of the word “Theory”

different than the everyday use of the word theory.

Scientific Terms•Law: A statement or equation that summarizes observations without explaining them.

Examples: –Law of conservation of matter–Laws of inheritance