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The Nature of Science & Science Skills Test Review

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Research starts with a … Research question –What the scientists wants to know

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What are the two general types of research: Experimental Descriptive

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Descriptive research is… Based mainly on observations

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Examples of descriptive research are… Making models Dissections Observing animals in the wild

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For example… How do the survivors of a disaster react to the disaster? No variables; data is based on watching and talking to survivors

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Experimental research is… The manipulation and control of variables

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Speaking of variables….

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What are the three types of variables? Independent variables Dependent variables Controlled variables –Also called constants

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Independent variables are… What is being tested What is being changed The difference between the groups The ‘cause’ of a change

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Dependent variables are… What is observed What is measured The data The ‘effect’ caused by the independent variable

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Controlled variables are… Things that could change, but don’t Kept constant by the scientist Allow for a fair test

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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

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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

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Predictions Educated guesses about what will happen during an investigation –Based on prior knowledge (observations, background research, etc)

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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.

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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?????????

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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

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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.

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The null hypothesis A statistical procedure Stated as if there will be no relationship between the variables

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For example… There is no relationship between water temperature and the speed of a hurricane

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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

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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

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TrialVariable 1Variable 2Variable 3 1 2 3 4 5 Average Title Describing the Data

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Analyzing the data Reduce the data –Do something to make the amount of data smaller Central tendencies –Mean (average) –Median –Mode –Range –frequency

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Analyzing the data Graph the data –Lets us see trends, patterns, relationships, comparisons –Bar graphs Let us compare data –Line graphs Let us see trends or changes –Scatter plots Shows correlations or associations between variables

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Bar graph This shows a comparis on of the types and amounts of trash found on a beach

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Line graph This shows a change in grade point averages; the trend is an increase in GPA

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Scatter plot Positive Correlation An increase in the variable on the X-axis is associated with an increase in the variable on the Y-axis

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Scatter plot Negative Correlation An increase in the variable on the X-axis is associated with an decrease in the variable on the Y-axis

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Scatter plot No Correlation Random data points – there is no association between the variables

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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

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

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