The Scientific Method

Scientific Method An organized approach used to solve a problem or solution. A list of steps that is not set in stone, rather it is used as a guide or frame for problem solving.

1. Hypothesis versus Theory Established idea Factual Experiments Data Hypothesis: A possible explanation of an observation Outcome If I do….then I expect…… correct or incorrect

Controlled Experiments Experimental Group: The part of the experiment in which a factor or variable is changed. Control Group: the part of the experiment that is left alone or “natural”. Used to compare back to

Variables Variables are parts of an experiment that can be changed. Control (constant variables): factors in an experiment that are NOT changed.

Experimental Variables: Independent (manipulated) Variable: factors in an experiment that are changed. Good experiments have only ONE manipulated variable. Dependent (responding) Variable: responds to changes in the independent variable. Example: Measure growth in height as a result of no fertilizer

Experimental Variables: Dependent Variable: Height Independent Variable  Fertilizer

DRY MIX DRY MIX Experimental Variables Acronym. The dependent variable is the one being tested. It is called dependent because it depends on the independent variable. Sometimes it is called the responding variable.

Observation vs. Inference Description of objects, events May include data from all five senses (touch/texture, smell, taste, sight, sound) Could be drawings, diagrams, measurements, written words Do not include opinions. Drawing conclusions based on observations Often provide a reason for the event/object being observed. Based on previous knowledge.

Data versus Opinion…... Data: Factual Measurable Replicates Opinion: Personal Inferences versus observations? bias

Qualitative vs. Quantitative Analysis is not based on numbers or measurement. Example: Rock composed of silica and quartz, yellow stars, liquid is composes of hydrogen and oxygen, ect.... Analysis based on measurement.  Example: 85 millimeters long, 12 cars, 342 million miles, etc.....

Accuracy vs. Precision Accurate Precise How close your measurements are to being correct. Refers to how close the measurements are to each other. You  can be very precise and not accurate at the same time.

Types of Experimental Errors Systematic errors Random Errors Constant throughout a set of readings. May result from equipment which is incorrectly calibrated or how measurements are performed. Cause average (mean) of measured values to depart from correct value. Difficult to spot presence of systematic errors in an experiment. An error that varies between successive measurements Equally likely to be positive or negative Always present in an experiment Presence obvious from distribution of values obtained Can be minimized by performing multiple measurements of the same quantity.

Scientific Data Must Be….. Measurable Quantifiable NOT opinion or judgment

7 Steps of the Scientific Method Problem or Question Research Hypothesis Experiment Collect and Analyze Data Conclusion Communicate Results

Identify the question What question is being answered, problem solved, or hypothesis tested? Leads to observations For example, “How many drops of water fit on a penny?”

Background research Research the problem using quality sources. Ask questions and read everything you can about the problem you have chosen. Study the method of measurement you will use to quantify your observations if it is one you are not familiar with.

State you hypothesis Construct a Hypothesis: A hypothesis is an possible solution about how things work: Based on research. "If _____[I do this] _____, then _____[this]_____ will happen." You must state your hypothesis in a way that you can easily measure, and of course, your hypothesis should be constructed in a way to help you answer your original question.

Design an experiment The experiment tests whether your hypothesis is true or false. It is important for the experiment to be a fair test. Conduct a fair test by making sure that you change only one factor at a time while keeping all other conditions the same. Repeat the experiments several times to make sure that the first results weren't just an accident.

Collect and Analyze data Once the experiment is complete, analyze the data to see if your hypothesis is true or false. Scientists often find that their hypothesis was false, and in such cases they will construct a new hypothesis starting the entire process of the scientific method over again. Even if they find that their hypothesis was true, they may want to test it again in a new way.

CONCLUSION A conclusion summarizes how the results support or contradict the original hypothesis. Summarize the results in a few sentences and use this summary to support or refute the hypothesis. Include key facts from your background research to help explain your results as needed. Summarize and evaluate your experimental procedure, making comments about its success and effectiveness. Suggest changes in the experimental procedure (or design) and/or possibilities for further study.

Communicate results Communicate the results to others in a final report. publishing their final report in a scientific journal presenting their results on a poster, or in some other form, at a scientific meeting.