Scientific Inquiry I. Scientific Knowledge a. Scientific Theory – an explanation for what we see, explains how or why something occurs. Example: The universe is expanding because objects in space are observed moving farther and farther away from one another. b. Scientific Law – an observable occurrence, a description of what we see happen. Example: Law of gravity – when we drop a ball, it falls c. Observation – an experience perceived through one or more senses. Example: we see a red ball, we hear thunder, we measure time d. Measurement – a number and a unit that define a quantity, such as length, volume, or mass. e. Inference – to construct a link between what is observed and what is already known. Example: one observes rabbit tracks in newly fallen snow; the inference is a rabbit has moved in the direction of the tracks since the snow has fallen. f. Opinion – A belief or judgment that is not supported with data or enough information to be completely certain. Example: It is too cold in the classroom. II. Experimental Design a. A good experiment: 1. tests one thing at a time. If more than one thing is tested at a time, it won’t be clear which one caused the end result. 2. must be fair and unbiased. This means that the experimenter must not allow his or her opinions to influence the experiment. 3. does not allow any outside factors to effect the outcome of the experiment. 4. Has an outcome (result) that can be measured (and sometimes observed). 5. Repeated trials-doing the experiment completely through several times to gather enough data to make a good conclusion. Repeating the experiment will reduce the effect of experimental errors. 6. An experiment will have at least two set ups, a control set up (or group) and an experimental set up (or group). The difference between the two set ups is the independent variable. b. Variable- anything in an experiment that can change or be changed; any factor that can have an effect on the outcome of the experiment. c. Independent Variable – the variable that is manipulated by the experimenter. (“I” change it) d. Dependent Variable – the variable that is measured in response to the independent variable. (“D” for determined or discovered) e. Controlled variable or constant – any factor that could change but is intentionally kept constant. (“C” for constant) f. Control – the part of the experiment used for comparison of results. 1. Not all experiments have a control, sometimes the control may be supplied by the results of another experiment or be supplied through research of facts (melting point, density, etc) g. Experimental Group– The group that receives the experimental treatment. Example: An experiment is testing the effect of temperature on the growth of plants. The plants are grown at three different temperatures. Each temperature condition is an experimental group. h. Hypothesis – a testable statement to a problem. 1. The hypothesis should either be a positive statement (Salt water boils at a higher temperature than fresh water) or a negative statement (Plants will not grow in the dark). 2. The hypothesis should address the IV and the DV i. Sources of error – are specific and directly effect the outcome of the experiment. j. Problem/Question – what we are trying to solve through experimentation. k. Models – used to show relationships in nature that are too large or too small for normal viewing. Example: atom models, Lewis dot diagrams, solar system models, mathematical equations l. Operational Definitions – defines an object by showing how it functions, works or behaves. Example: A ruler can be defined as a tool that measures length of an object (how it’s used); a ruler can also be defined as something that contains a series of marks that can be used as a standard when measuring (how it works). III. Analyzing Data a. Data – recorded observations and measurements b. Data tables should compare the independent variable to the dependent variable. c. There are three types of graphs that are used to display and compare information. 1. Bar graphs – compare data that do not change continuously. 2. Circle graphs – or pie charts use a circle divided into sections to display data as parts (fractions or percentages) of a whole. 3. Line graphs – used to show the relationship between variables as they change over time. d. Graphs – relate the independent variable to the dependent variable 1. Graphs should be neat and easy to read and constructed with a straightedge or with a computer. 2. All graphs have a title 3. The axes are labeled with words that explain the numbers on the axes. 4. The units (numbers marked on the axes) follow equal intervals, however different axes do not have to be divided by the same scaled increment 5. Scales do not have to start at zero 6. Graphing Data does not mean dot connecting, rather look for trends. 7. Trends in data should be stated as: When the ____(x) increases, the _____(y) goes ____. IV. Scientific Investigations a. Scientific Method – a problem solving method scientists use to study and learn about the world around them. There are usually 6 parts: 1. Purpose or Question 2. Research - process of collecting and gathering information about the problem before forming a hypothesis. 3. Hypothesis 4. Procedure – the plan you follow in the experiment. a. This must be written clearly so that another person could do the experiment exactly the same way you did. b. Must include a materials list with exact amounts needed to perform experiment. 5. Analysis - Record what happened during the experiment. 6. Conclusion a. Review observations and measurements. b. Determine whether the data supports the hypothesis. c. Develop an explanation for why the results occurred. a. Connect your observations to your research through inferences.
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