1.2 Using a Scientific Approach
Scientific Methods
An organized plan for gathering, organizing, and
communicating information is called a scientific
method.
• Scientific methods can vary from case to case, depending
on the question and how the researcher decides to look
for an answer.
• The goal of any scientific method is to solve a problem or
to better understand an observed event.
1.2 Using a Scientific Approach
Scientific Methods
Here is an example of a
scientific method. Each step
uses specific skills. The
order of steps can vary.
Sometimes you will use all of
the steps and other times
only some of them.
1.2 Using a Scientific Approach
Making Observations
An observation is information that you obtain through your
senses.
Forming a Hypothesis
A hypothesis is a proposed answer to a question.
Testing a Hypothesis
• The manipulated (independent) variable causes a
change.
• The responding (dependent) variable changes in
response to the manipulated variable.
• A controlled experiment is an experiment in which only
one variable, the manipulated variable, is deliberately
changed at a time.
1.2 Using a Scientific Approach
Scientific Methods
Drawing Conclusions
A conclusion describes how facts apply to a
hypothesis.
Developing a Theory
A scientific theory is a well-tested explanation for a
set of observations or experimental results.
Scientific Law
A scientific law is a statement that summarizes a
pattern found in nature. The explanation of such a
pattern is provided by a scientific theory.
1.2 Using a Scientific Approach
Scientific Models
A model is a representation of an object or event. A
street map is a model of a city.
Scientific models make it easier to understand
things that might be too difficult to observe directly.
Models help you visualize things that are too small
to see, such as atoms, or things that are very large,
such as the solar system.
An example of a mental, rather than physical,
model might be that comets are like giant snowballs,
primarily made of ice.
1.2 Using a Scientific Approach
Using Scientific Notation
Why is scientific notation useful?
Scientists often work with very
large or very small numbers.
Astronomers estimate there
are 200,000,000,000 stars in
our galaxy.
1.2 Using a Scientific Approach
Using Scientific Notation
Scientific notation is a way of expressing a value as
the product of a number between 1 and 10 and a
power of 10.
For example, the speed of light is about 300,000,000
meters per second. In scientific notation, that speed is
3.0 × 108 m/s. The exponent, 8, tells you that the
decimal point is really 8 places to the right of the 3.
1.2 Using a Scientific Approach
Using Scientific Notation
For numbers less than 1 that are written in
scientific notation, the exponent is negative.
For example, an average snail’s pace is 0.00086
meters per second. In scientific notation, that speed is
8.6 × 10-4 m/s.
The negative exponent tells you how many decimals
places there are to the left of the 8.6.
1.2 Using a Scientific Approach
Using Scientific Notation
To multiply numbers written in scientific notation:
multiply the numbers that appear before the multiplication
signs
add the exponents
This is about the distance between the sun and Earth.
1.2 Using a Scientific Approach
Using Scientific Notation
To divide numbers written in scientific notation:
divide the numbers that appear before the multiplication
signs
subtract the exponents
The following example demonstrates how to calculate the time
it takes light from the sun to reach Earth.
1.2 Using a Scientific Approach
Using Scientific Notation
Using Scientific Notation
A rectangular parking lot has a length of 1.1 × 103
meters and a width of 2.4 × 103 meters.
Q: What is the area of the parking lot?
A: 2.64 × 106