The Nature of Science The Nature of Science & &

Science SkillsScience Skills

Review

Research starts with a …

• Research question– What the scientists

wants to know

What are the two general types of research:

• Experimental• Descriptive

Descriptive research is…

• Based mainly on observations

Examples of descriptive research are…

• Making models

• Dissections

• Observing animals in the wild

For example…

How do the survivors of a disaster react to the disaster?

No variables; data is based on watching and talking to survivors

Experimental research is…

• The manipulation and control of variables

Speaking of variables….

What are the three types of What are the three types of variables?variables?

• Independent variables

• Dependent variables

• Controlled variables– Also called constants

Independent variables are…

• What is being tested

• What is being changed

• The difference between the groups

• The ‘cause’ of a change

Dependent variables are…

• What is observed

• What is measured

• The data

• The ‘effect’ caused by the independent variable

Controlled variables are…

• Things that could change, but don’t

• Kept constant by the scientist

• Allow for a fair test

So an experimental question has to indicate the variables

• How the independent variable will AFFECT the dependent variable

• What the EFFECT of the independent variable will be on the dependent variable

For example…

• How does the temperature of ocean water affect the speed of a hurricane?– Independent variable

• T of ocean water

– Dependent variable• Speed of a hurricane

Predictions

• Educated guesses about what will happen during an investigation– Based on prior knowledge (observations,

background research, etc)

For example…

People in disasters will react by trying to help others as much as possible.

This is a PREDICTION because it’s a guess about what you think will happen.

Hypothesis(plural – hypotheses)

• Special kind of prediction

• What makes it so special???– It’s a guess about the VARIABLES & their

relationship, in particular,• How will the independent variable affect the

dependent variable?????????

How to write a hypothesis

• Use an If, Then statement

• IF the independent variable changes, THEN the dependent variable changes– This type of sentence shows what the IV will

do to the DV

For example…

• IF the T of ocean water increases, THEN the speed of a hurricane will increase.

• This shows the expected relationship between the independent variable (the T of ocean water) and the dependent variable (the speed of a hurricane)– If the T of ocean water changes, it will cause

the speed of a hurricane to change too.

Planning the investigation – Experimental Design

• You absolutely, positively have to know what the variables are!– What you are changing

• How you are changing

– What you are measuring• How you are measuring

– Repeated trials– Data tables

Data tables?

• Numerical (quantitative) data organized in rows and columns

• The specific independent variables are listed

• The number of trials are listed

• Blanks are left for the data (dependent variable) to be filled in

Trial Variable 1 Variable 2 Variable 3

1

2

3

4

5

Average

Title Describing the Data

Analyzing the data

• Reduce the data– Do something to make the amount of data

smaller• Central tendencies

– Mean (average)– Median– Mode– Range– frequency

Analyzing the data

• Graph the data– Lets us see trends, patterns, relationships,

comparisons– Bar graphs

• Let us compare data

– Line graphs• Lets us see trends or changes

Bar graph

This shows a

comparison of types and amount of trash on a

beach.

Line graph

This shows how the grade point

average has been changing

over several years. The trend is an increase in

GPA.

Conclusions

• How we sum up the investigation– Does the data support the hypothesis?

• If it does – we accept the hypothesis• If it does not – we reject the hypothesis

– All back up what you say with data• Evidence

– Discuss issues or problems with the investigation

– Discuss the importance or relevance of the investigation

Communicate what you know

• Finding out something new doesn’t do anyone any good unless the new knowledge is shared– Journals & magazines– Presentations