Methods of Scientists
Chapter 1.2 and 1.3
Scientific Investigations
Common steps used to gather information and answer questions.
1. 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.
• 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.
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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.