Methods of Scientists Chapter 1.2 and 1.3

Scientific Investigations Common steps used to gather information and answer questions. Problem 2. Collect Information 3. Hypothesis – If ….then form Variable follows the If Expected results come after “then” Must be TESTABLE.

4. Controlled Experiment Control is for COMPARSON – left alone Variable – the ONE thing that changes 1. Independent variable – what you change Goes on the X axis of a graph 2. Dependent variable is what you measure Goes on the Y axis of a graph

Data – usually in the form of a graph or chart.

Conclusion – refers back to the hypothesis Can only conclude if HYPOTHESIS was correct or incorrect. Report 1. Would be published by a scientist 2. This is what students turn in to teacher. Repeat – by others for VALIDITY

Measurement – Done in SI (Modern Form of Metric System) Length. 1. Standard unit I meter (m). 2. Measured with a meter stick. Weight and Mass. 1. Weight varies with location – measure of pull of gravity. 2. Mass is the amount of matter in an object. 3. SI Unit. a. Mass = kilogram (Kg). b. Weight = Newton (N).

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Area and Volume Area = L x W. 1. Measured in square units (cm2, m2). Volume = L x W x H. 1. Measured in cubic units (cm3) or in ml.

Density A measure of the amount of matter that occupies a given space.                                                                                                                                                                                                       Density A measure of the amount of matter that occupies a given space. D = M/V. Measured in g/cm3 or g/ml.

Time – the interval between events. 1. Usually measured with a watch or clock. 2. Second (s) is the unit . Temperature – measure of the average vibrations of the particles that make up a material. 1. Measured with a thermometer. 2. Unit is degrees (Fahrenheit or Celsius). 3. In SI, temperature is measured on the Kelvin scale. a. Coldest possible temperature (where all molecular motion stops) is absolute zero (-273oC).

Scientific Notation Expresses a number as a multiplier and a power of 10. Only 1 number remains to the left of the decimal point. 1. If the decimal is shifted LEFT, the exponent is positive. 2. If the decimal is shifted RIGHT, the exponent is negative. Click in box to play movie

Communicating in Science Allows others to learn of new discoveries or to verify reports. Types of communication: 1. Lab reports. 2. Graphs. a. Independent variable on X axis. b. Dependent variable on Y axis.

Models – change with new data. Theories and Laws. 1. Theory – explanation based on many observations during repeated experiments. 2. Law – basic fact that describes the behavior of nature or a “rule of nature.” 3. Theories often explain scientific laws.