Scientific Method Notes

The Scientific Method  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.

The Steps of the Scientific Method  Ask a Question  Do Background Research  Construct a Hypothesis  Test Your Hypothesis by Doing an Experiment  Analyze Your Data and Draw a Conclusion  Communicate Your Results

The Scientific Method Itself  Observations:  Whether they start with a problem or not, scientists make careful observations.  Observations are a way to collect data (recorded observations or information) about events or processes in a careful, orderly way, using the senses (sight, hearing, touch, taste and smell).

Two types of data include:  Quantitative data: Are observations which collect data that can be directly measured or counted.  Qualitative data: Are observations involve making careful descriptions or drawings and do not involve numbers.  Inference: A logical interpretation of an observation based on prior knowledge. An educated guess as to what is occurring.

 Hypothesis:  A proposed scientific explanation for a set of observations. Scientists devise hypotheses based on logical inferences, prior knowledge and informed, creative imagination.  Hypotheses may be tested by controlled experiments, or by collecting additional data.

A Good Experiment  Tests one variable at a time. If more than one thing is tested at a time, it won’t be clear which variable caused the end result.  Must be fair and unbiased. This means that the experimenter must not allow his or her opinions to influence the experiment.  Does not allow any outside factors to affect the outcome of the experiment.

 Is valid. The experimental procedure must test your hypothesis to see if it is correct.  If the procedure does not test your hypothesis, the experiment is not valid and the data will make no sense!  Has repeated trials. Repeating the trials in the experiment will reduce the effect of experimental errors and give a more accurate conclusion.

Variables  A variable is anything in an experiment that can change or vary.  It is any factor that can have an effect on the outcome of the experiment.  There are three main types of variables.

3 Kinds of Variables  Independent Variable/Manipulated  Dependent Variable/Responding  Controlled Variables/Control Group

Independent Variable Something that is intentionally changed by the scientist What is tested What is manipulated You can only change ONE variable in an experiment!!! To determine the independent variable, ask yourself: “What is being changed?”

Independent Variable Example: Assume you are testing five brands of popcorn to see which has the most unpopped kernels.  The Independent Variable would be the different brands of popcorn.

Dependent Variable Something that might be affected by the change in the independent variable What is observed and measured The data collected during the investigation To determine the dependent variable, ask yourself: “What will I measure and observe?”

Dependent Variable Example: Assume your dependent variable in an experiment is “plant growth.” How will you measure this?! It could be…  Height (cm), mass (g), # of leaves, etc.  Be specific and include all necessary units!

Controlled Variable A variable that is not changed and kept the same Allows for a “fair test” NOT the same as a “control”!! Any given experiment will have many controlled variables To determine the controlled variables, ask yourself: “What should not be allowed to change?”

What is a Control A group or individual in the experiment that is not tested, but is used for comparison as a reference for what “normal” would be like. Not all experiments have a control (though all experiments have controlled variables). Example: If you tested different pollutants to see their affect on plant growth, the control would only receive water.

Example One:  Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle. Identify the variables in this investigation!

What was the independent variable? Ages of the students/Different ages were tested by the scientist What was the dependent variable? The time it to put the puzzle together/The time was observed and measured by the scientist What was a controlled variable? Same puzzle/All of the participants were tested with the same puzzle/It would not have been a fair test if some had an easy 30 piece puzzle and some had a harder 500 piece puzzle.

Example Two:  An investigation was done with an electromagnetic system made from a battery and wire wrapped around a nail. Different sizes of nails were used. The number of paper clips the electromagnet could pick up was measured. Identify the variables in this investigation!

What was the independent variable? Sizes of nails/These were changed by the scientist/They used different sizes of nails in their experiment to see what effect that would have. What was the dependent variable? Number of paper clips picked up/The number of paper clips were observed and counted (measured) What was the controlled variable? Battery, wire, type of nail/None of these items were changed/They had used the same battery, same wire, and same type of nail/Changing any of these things would have made it an unfair test.

Example Three:  The temperature of water was measured at different depths of a pond.

 What is the independent variable? depth of the water  What is the dependent variable? Temperature  What is the controlled variable? same pond; same thermometer

Independent Variable Dependent VariableDependent Variable A typical scientific graph Measured variables are plotted from the Y axis (lengths, weights, speed numbers) Variables like time and dates that don’t depend upon other variables are plotted via the X axis

Example One of Variables

Example Two of Variables

 Conclusion: written paragraph summarizing the results of the experiment.  Theory: A well-tested explanation that unites a wide range of observations.  Model: physical, mental or mathematical representation of how people understand a process or an idea.

Scientific Method Notes

The Scientific Method  Science________________________ ______________________________ _____________________________.  The goal of science ______________ ________________________________ ______________________________ ______________________________ _____________________________.

The Steps of the Scientific Method  _________________________

The Scientific Method Itself  Observations:  ______________________________ ______________________________ _____  Observations are a way to _________ _______________________________

Two types of data include:  Quantitative data: ______________ _______________________________.  Qualitative data: ________________ _______________________________.  Inference: _____________________ _______________________________ _______________________________.

 Hypothesis:  _____________________________ _____________________________ _____________________________.  Hypotheses may be______________ _____________________________ _____________________________

A Good Experiment  Tests ___________ at a time. If more than one thing is tested at a time, it won’t ______________________________________ _______________________________.  Must be ______________________. This means that the experimenter ___________ _____________________________________  Does not allow _________________________ ________________________________________.

 Is ____. __________________________. ___________________________________  If the procedure does not test your hypothesis, ________________________ __________________________________!  Has __________. Repeating the trials in the experiment _____________________ ____________________________________ _________________________________.

Variables  A variable is anything in an _________ _________________________________.  It is any factor ___________________ __________________________________.  There are _____________ of variables.

3 Kinds of Variables  _____________________________

Independent Variable Something that is ___________________ _________________________ ______________________________!!! To determine the independent variable, ask yourself : “_____________________________?”

Independent Variable Example: Assume you are testing five brands of popcorn to see which has the most unpopped kernels.  The Independent Variable would be the different brands of popcorn.

Dependent Variable Something that might be affected ________________ ___________________________________________ What is ________________________ _________________________________ To determine the dependent variable, ask yourself: “_________________________________?”

Dependent Variable Example: Assume your dependent variable in an experiment is “plant growth.” How will you measure this?! It could be…  _______________________________.  Be specific and include all _____________!

Control Group _________________________________ Allows for a “_____________” _______________ as a “CONSTANT”!! Any given experiment will have many controlled variables To determine the controlled variables, ask yourself: “________________________________________?”

What is a Control Group A group or individual in the experiment that __________, but is used for __________ _________ for what “normal” would be like. Example: If you tested different pollutants to see their affect on plant growth, the control would only receive water.

Example One:  Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle. Identify the variables in this investigation!

What was the independent variable? __________________________________ What was the dependent variable? _____________________________________ What was a controlled variable? _____________________________________ ____________________________________

Example Two:  An investigation was done with an electromagnetic system made from a battery and wire wrapped around a nail. Different sizes of nails were used. The number of paper clips the electromagnet could pick up was measured. Identify the variables in this investigation!

What was the independent variable? _____________________________________ _____________________________________ _______________ What was the dependent variable? ___________________________________ What was the controlled variable?_____________________________________

Example Three:  The temperature of water was measured at different depths of a pond.

 What is the independent variable? ____________________________  What is the dependent variable? _____________________________  What is the controlled variable? _____________________________

Independent Variable Dependent VariableDependent Variable A typical scientific graph Measured variables are plotted from the Y axis (lengths, weights, speed numbers) Variables like time and dates that don’t depend upon other variables are plotted via the X axis

Example One of Variables

Example Two of Variables

 Conclusion: written paragraph summarizing the results of the experiment.  Theory: A well-tested explanation that unites a wide range of observations.  Model: physical, mental or mathematical representation of how people understand a process or an idea.