What is Science? Intro 1.1 pp 3-10 Standard 1.1 pp 4-9 Mr. Richter

Agenda  Collect  Lab Safety Contracts  Data and Measurement Sheets  Did you get a Newsflash?  Warm-Up  Notes:  What is Science?  The Scientific Method  Variables  Systems and Models

Objectives: We Will Be Able To…  Define “Science”.  Give a reasonably detailed description of the scientific method.  Differentiate between and identify independent, dependent, experimental and control variables.  Define systems and construct conceptual models of systems.

Warm-Up: Design An Experiment  Joey heard about a sweet new Nike sneaker coming out that is supposed to improve one’s ability to jump higher. He wants to convince his whole basketball team to buy them, but he doesn’t want to be cheated. How can he find out if the new sneaker does what it says?  With your tablemates, discuss some ways Joey could investigate the sneaker. Then, write a 2-3 sentence description of how Joey could conduct the investigation. After a few minutes, we will share with the class.

Science What is it?

What is Science?  What you said:  Involves discovery  New technology  Proving things  Experiments  Testing  Exploration

How Scientists Define Science  Narrow view: any field that applies the scientific method to conduct experiments.  Problem one: circular argument. Don’t use the word scientific to define the word science.  Problem two: this view excludes fields like geology, which is more exploratory or observational, and less experimental.  Broad (better) view: "the field of study which attempts to describe and understand the nature of the universe in whole or part.”  -JP Siepmann, Editor, Journal of Theoretics

The Scientific Method

 Ask a question.  Formulate a hypothesis.  Design a procedure to test the hypothesis.  Conduct the experiment and collect the data.  Analyze the data.  Use the data to make a conclusion.  If necessary, refine the question and go through each step again.

Question  Basically, what is the effect of one thing on another, if any? Something that can be tested.  For example:  Does smoking cigarettes cause cancer?  Is the amount of traffic at the bottom of the hill worse depending on the day?  If my little brother gets punched, will he bring me a cookie?  In your notes, write a question that compares the effect of one quantity on something else.

Hypothesis  In short, a testable, measureable statement. It predicts the relationship between variables in an experiment (more about variables later).  For example,  Smoking cigarettes increases the likelihood of cancer.  Traffic is worse on Fridays than on Mondays.  My little brother will bring me a cookie if he gets punched.  In your notes, take your question from before and turn it into a hypothesis.

Procedure  A step-by-step list of how you will test your hypothesis.  This should be incredibly detailed, so anyone could follow the steps and achieve the same results that you did.  A procedure is the recipe for scientific discovery.

Conduct the Experiment  Actually follow the procedure.  Collect your data impartially and record it.

Analyze Data  Look at what your data tells you. Look for trends and patterns.  Sometimes information will not be immediately obvious, especially if your data is numerical. Analysis can be as simple as graphing on an x-y plane, or it can be very complicated.

Conclusion  Based on your analysis, decide whether or not your hypothesis is correct.  Yes, smoking causes cancer.  Yes, traffic is worse on Fridays.  No, my little brother will not bring me a cookie if punched.  Note: if you can make a conclusion, there is no such thing as a failed experiment. Every experiment proves that something happens or something doesn’t happen. This is science!

Revise and Repeat  Most questions are not answered with one experiment.  Or sometimes, the question changes after more information is gathered through experimentation.  Does smoking 1 cigarette a day have the same effect as 5?  What will get my little brother to bring me a cookie?  Change the question, or change the procedure, and go again!

Variables

 In a hypothesis, we make a statement about one quantity’s effect on another. We are making a statement about variables.  The variable that causes change in the experiment is the independent variable.  The variable which shows, or maybe doesn’t show, the change is called the dependent variable.

Variables  Most hypotheses can be written in the form of:  If the (independent variable) is increased/decreased, then the (dependent variable) will increase/decrease.  For example:  If the height from which a ball is dropped is increased, the speed at which it collides with the ground will increase.

Variables  The more things that change in an experiment, the more difficult it will be to conclusively say that one thing has a definite effect on another thing.  For example, if I want to see how long a block of ice takes to melt, but I keep changing the amount of ice, or what room, or what stopwatch I use, I might get a confusing collection of results.  For this reason, experiments are designed so they have as few things that change as possible.

Variables  The variables that change in an experiment are called experimental variables, which include the independent and dependent variables.  In our example from before, the height of the ball and the with which speed it hits the ground are the experimental variables.  The variables that do not change in the experiment are called control variables.  In the same example, this would be using the same ball, at the same temperature, dropped by the same person, and so on.

Variables  Any variables that complicate or “muddy” the results are called confounding variables, because they confound the data. Avoid these. They are bad.  Confounding variables exist when variables that should be controlled are not. Much of the mental energy for experimental design goes into avoiding confounding variables.

Systems and Models

Systems  When studying the relationship between two or more things, it is useful to decide what matters and what doesn’t.  For instance, when we measure the speed of a car rolling down a ramp, the things that matter are the car, the ramp, the angle, the speed, time and mass.  These things make up the system: a set of items or interactions considered a distinct physical entity for the purpose of study.  The system is made up of the things that matter in a study.

Outside the System  Things that don’t matter to the science we exclude from the system.  The color of the car, the brand of the table and the window have no effect on the results.  Sometimes we exclude things that have a small effect on the results, like wind or friction.

Models  We experiment and study systems to measure one variable’s effect on another. Ideally, at the end of an experiment, we can produce a model that represents this effect.  Conceptual models state in words the basic idea of what is happening.  “When heat is added to ice it gets warmer then turns into water.”  Numerical or mathematical models express things more precisely.  “When 4,186 Joules of energy is used to heat 1 kg of water, its temperature will rise 1 degree Celcius.”

Wrap-Up: Did we meet our objectives?  Science attempts to describe the nature of the universe.  Science is conducted using the scientific method, from questions to conclusions.  Dependent variables depend on independent variables. Both of these are experimental variables.  Systems are defined to observe the effect of one variable on another.

Homework  Intro  p10 #3  p24 Vocabulary #4,6  p24 Concepts #8, 11, 12  p25 #1  Standard  p27 #2-4