Scientific InvestigationsThe Nature of Scientific Research

Science Builds on Good Observations

• May be done by observing and reflecting on what other scientists have done

• May be done by one’s own careful and thoughtful observations (seeing what others do not see)

• May be done by making inferences on what you observe.

Can you think like a scientist?Test your own powers of observation next →

Look at these five trees closely. Identify some testable hypotheses that can you generate?

Hints to Find Three Hypotheses:

• Think about the different sizes of the trees• Think about the number of trunks each tree has• Think about how the two smaller trees differ

from each other• Think about the bushes growing under the trees

• Go to next slide and look at picture again. Write at least 3 hypotheses to share with class.

Good Research is Hypothesis-Driven.

What does this mean?

Why is it true?

So What is a Good Hypothesis?

• Based on observations, inferences and previous knowledge.

• Must be written as an if/then statement.

• Is a predictable or logical conclusion/result.

• Is testable.

• Found to be right or wrong at end of investigation.

A possible explanation for an observation or a scientific problem. . .

Science is a Cyclic Process:

Observe

Hypothesize

Design Test of

Hypothesis Conduct Experiment

Analyze Data

Ask Questions/ Identify the

Problem

Hypothesis Example• Fact: we know that plants need water.

• Hypothesis: If a plant is watered more frequently , then it will grow faster.

• Test: Set up a test with 2 of the same kind of plant in the same pots and in same place of room. Give one plant a normal amount of water (record amount) necessary for growth and give one plant an increased amount (you must record how much you increase it by) observe over a period of time and record results.

• You must have a control group and only one variable tested at a time!!

3 Types of Investigations:• Experimental Investigation- – Involves a process in which

a “fair test” is designed in which variables are actively manipulated, controlled, and measured in an effort to gather evidence to support or refute a causal relationship.– The plant will grow faster IF copper is added to soil.

• Comparative Investigation – Involves collecting data on different populations/organisms or under different conditions to make a comparison:– Dogs prefer wet food over dry food.

• Descriptive Hypothesis – Involve describing and/or quantifying parts of a natural system and conditions can not be changed or manipulated:– More moss grows on the side of rocks in shady wet

areas than on the side of rocks in sunny dry areas.

How to Design an Experiment

• Experiment must test the hypothesis.

• Account for all known variables.

• Have a control group.

• Make sure you have the tools needed to perform the experiment.

How do we test and control what happens in our experiments so the results can be trusted?

Testing HypothesesAccount for the “Variables”

• Variables are factors or conditions that can vary and thus influence the results.

• Only one variable should be tested at a time.

• 3 Kinds of variables:

– Independent variable = what you change or manipulate

– Dependent variable = changes because of independent variable changing or responding variable (depends on the independent)

– Constants/controlled variables = no changes at all, these must all be kept the same in experiment

Testing Hypotheses Continued• In addition to your variables, you must also have a

Control Group.

– A control group is an additional experiment run where no changes will be made to any of the variables.

– This gives the scientist the ability to compare the results gathered from the tested group or item against a “normal” group.

– This is how scientists determine if their independent variable is causing any effects on their experiment.

Example for Control GroupFrom Plant With Copper Added to Soil Hypothesis:

• The Control Group will be another of the same plants with all the same variables as tested plant, EXCEPT, it will have NO COPPER added to its soil at all. It will serve as the “normal” situation. The tester will compare his/her results from the tested plant to the plant that is “normal”.

Plant with no copper added

Plant with copper added

Control Group Test Group

Example:

Graphing Results:

Students can easily plot their results on to a graph!

Experiment

Let’s find out what happens when we conduct the tests!!

Analyze the Results

• Describe what happened in the experiment.

• Display results using graphs, tables, map, and charts.

• Perform any calculations necessary to clarify the data.

Common Interpretation Errors

• Assuming that if two events occur together, one must be causing the other.

• Failure to consider alternative explanations.

• Extending conclusions beyond what is supported by the data.

Science is a Way of Knowing

• QUESTION: What would happen if .....?

• HYPOTHESIS: If…happens, then…will happen.

• EXPERIMENT: Make observations, Collect the data.

• ANALYSIS: What actually happened? What do these results mean?

• CONCLUSION: The hypothesis was correct/incorrect because.....

The process of research can involve several steps. These levels are summarized below.

In Science, Decisions are Based on Evidence!

Everybody Can Think Like a Scientist

• Observe. Listen. Read.• Ask questions.• What is the evidence? • Do I have access to all the evidence?• Is the evidence good?

How much evidence is there? Is evidence based on fact or opinion? Does evidence come from several INDEPENDENT

sources?

• How can I test to see if the evidence is correct?

Theories in Science

• Theories can be more important than isolated facts.

• Theories guide the direction of research, providing the context in which ideas and hypotheses are generated.

• Good theories show how many isolated facts are compatible and consistent with each other.

• Good theories stand the test of time, but may be replaced when a better theory comes along.

Interesting Websites:• http://boyslife.org/hobbies-projects/funstuff/2184/weird-

science/comment-page-5/

• http://sciencecastle.com/sc/index.php/rooms/view/6

• http://www.tnmanning.com/Test/Tests/scientific_inquiry_process.htm

• http://nces.ed.gov/nceskids/createagraph/default.aspx?ID=3f359c1f0dae49e0b31f3ba396f73cb2

Make science fun and safe!!

• Independent v. – you change in the experiment

• Dependent v. – it changes as a result of the independent changing

• Control – does NOT change

• Theory – an educated guess (with some possible support)

• Law – rule of science / proven theory

• Hypothesis – if/then statement – educated guess