2.  Although scientists do not always follow
a rigid set of steps, investigations often
follow a general pattern. An organized
set of investigation procedures is called
a scientific method. Six common steps
are found in scientific methods shown in
the next slides. A scientist might add
new steps, repeat some steps many
times, or skip steps all together when
doing an investigation.

3.  Many scientific investigations begin when someone
observes an event in nature and wonders why or how it
occurs. Then the question of “why” or “how” is the
problem. Sometimes a statement of a problem arises from
an activity that is not working. Some early work on guided
missiles showed that the instruments in the nose of the
missiles did not always work. The problem statement
involved finding a material to protect the instruments from
the harsh conditions of flight.
 Later, NASA scientists made a similar problem statement.
They wanted to build a new vehicle—the space shuttle—
that could carry people to space and back again.
Guided missiles did not have this capability. NASA
needed to find a material for the outer skin of the space
shuttle that could withstand the heat and forces of reentry
back into Earth’s atmosphere.

4.  Before testing a hypothesis, it is useful to
learn as much as possible about the
background of the problem. Have others
found information that will help determine
what tests to do and what tests will not be
helpful? The NASA scientists gathered
information about melting points and other
properties of the various materials that
might be used. In many cases, tests had to
be performed to learn the properties of
new, recently created materials.

5.  A hypothesis is a possible explanation for
a problem using what you know and
what you observe . NASA scientists knew
that a ceramic coating had been found
to solve the guided missile problem.
They hypothesized that a ceramic
material also might work on the space
shuttle.

6.  Some hypotheses can be tested by
making observations. Others can be
tested by building a model and relating
it to real-life situations. One common
way to test a hypothesis is to perform an
experiment. An experiment tests the
effect of one thing on another using
controlled conditions.

7.  Open another window and go to the
following website.
http://nces.ed.gov/nceskids/help/user_g
uide/graph/variables.asp
 Use this website to define the following
terms.
› Independent variable
› Dependent variable

8.  Visit the websites below and read about
constants and the control group.
› http://www.monarchlab.org/mitc/Resources/Stu
dentResearch/ScientificMethod.aspx
› http://www.ehow.com/info_8003575_constants-
controls-science-project-experiment.html
 After reading from both sites, write a
definition for the terms below.
› Constant
› Control (or control group)

9.  We will work on independent and
dependent variables, constants, and
controls more together in class!

10.  An important part of every experiment includes
recording observations and organizing the
data into easy-to-read tables and graphs. In
the next couple of days, you will learn about
ways to display data.
 Interpreting the data and analyzing the
observations is an important step. If the data
are not organized in a logical manner, wrong
conclusions can be drawn. No matter how
well a scientist communicates and shares
data, someone else might not agree with the
data. Scientists share their data through
reports, journals, and conferences.

11.  Based on the analysis of your data, you
decided whether or not your hypothesis is
supported. When lives are at stake, such as
with the space shuttle, you must be very
sure of your results. For the hypothesis to be
considered valid and widely accepted, the
experiment must result in the same data
every time it is repeated. If your experiment
does not support your hypothesis, you must
reconsider the hypothesis. Perhaps it needs
to be revised or your experiment needs to
be conducted differently.