Scientific Method
The Steps to Problemsolving in Scientific
Research
Definition
Scientific Method
The common steps that
scientists use to gather
information to solve problems.
1. PROBLEM
(QUESTION or OBSERVATION)
A
question must be asked or a
situation must be observed to
begin the “experiment.”
Possible Observations…
*
When “miracle-gro” is put on
tomato plants, they grow into
bigger plants produce better
tomatoes
…Possible Questions?
*Is
it really the
“miracle-gro”?
2. RESEARCH
• Gather
information to
develop hypothesis.
• Inform yourself
•
What is miracle gro?, How does it
work? What is suppose to do?
3. HYPOTHESIS
oA
testable explanation for a
question or problem.
***NOT an “educated guess”***
Possible hypothesis
 When
placed on tomato plants and all
other conditions (water, light, temp.,
soil) are stabilized, the miracle-grow will
help to produce better plants.
4. EXPERIMENT….
(or collection of data)
A
procedure that tests a
hypothesis by the process of
collecting information under
controlled conditions.
A controlled experiment
2
parts
a.
control group
b. experimental group
a. Control group
 “The
standard” -- in which all
conditions are kept the same
 *Ex.-
the plants without the
“miracle-gro”
b. Experimental group
“The test group” -- in which all
conditions are kept the same
except for the single condition
being tested.
*Ex.- plants have “miracle-grow” added
Variables of controlled experiment
1.
Independent variable – the condition of
the experiment that is changed.
(ex: the “miracle gro”)
2. Dependent variable – the condition that is
observed/measured as result of the
changed independent var.
(the size of the tomatoes)
Hints for good experiments
 Always
follow safety guidelines
 Make careful and detailed
observations
 Take precise notes of observations
 Take precise recordings of numerical
data
…more hints
 Keep
recordings/observations
“honest”
 Have an appropriate sample size
 Keep an open mind
 Continually ask questions
 THINK!
5. ANALYSIS
Numerical
data and
observations are analyzed.
Interpret the data
Graphs, charts, etc may be
created during this step.
6. CONCLUSION
(Results)
Summarize the observations and data.
 Make sure to state weather your hypothesis was
correct or incorrect.
 If it was correct you may begin to:




Share findings with colleagues and fellow scientists
May publish the findings in scientific journals
Other scientists will attempt to duplicate the
experiment to “accept” the findings
7. Application

Apply the results to a real life situations

Some books/scientist really use this step
some do NOT…if its just for you to know
8. THEORIES & LAWS
A theory is an explanation of a natural
phenomenon that is supported by a
large body of scientific evidence
obtained from many different
investigations and observations.
 Experiment has been proven time and
time again
8. cont.
A
law or principle are facts of
nature.
 Ex.
– an apple falls from a tree to
the ground  the law of gravity
Types of Data
Quantitative Data- are expressed as
numbers.
 Qualitative data: are descriptive and
involve characteristics that usually cannot
be counted.

Measurement Systems
A measurement must include a number and a
unit
 Science uses the metric system for all
measurements – International system of units
or SI units – this is used worldwide
 In SI units, each type of measurement has a
base unit
 A standard, an exact quantity, is used for
comparisons

SI Base Unit

Quality Measured
Length
 Mass
 Time
 Electric Current
 Temperature


Unit
meter
Kilograms
Seconds
ampere
kelvin
Amount of Substance
mole
Symbol
m
kg
s
A
K
mol
To use the metric system you
must know the prefixes
The SI system is use because it is based
on multiples of 10.
 The prefix helps to determine what
multiple of 10 to use



Kilo means 1000 so 1 Kilogram = 1000 grams
Deci means .1 (1/10) so 1 Decimeter= 1/10 of a
meter or .1
To use the metric system you
must know the prefixes
Base (meter,liter,gram)
 Kilo
k
 Hecto
h
 Deka
da
 Deci
d
 Centi
c
 Mili
m

1,000
100
10
.1
.01
.001
To use the metric system you must
know the prefixes

Always remember this stair step method
How to convert units….
A rope that measure 3,075 mm. How long
is it in centimeters?
 You Know: 1m = 10 dm = 100 cm=


1000mm
Questions: 3075mm = ? cm
How to convert units….this is easier
To convert from a
larger number to a
smaller number,
move the decimal to
the right
 Ex. 5.32 m to cm
 Answer 532 cm

To convert from a
smaller number to a
larger number, move
the decimal to the left
 Ex. 7.5 cm to km
 Answer: .000075 km

Length




Length is the distance
between two points
SI unit is meter (m)
Size of unit that is used
will depend on what is
being measured
It is easier to measure
distance in kilometers
than in meters.
Mass
Measurement of
matter in an object
 SI unit is a kilogram
(kg)
 A gram is such a
small unit that it is
only used to
measure small
masses
 Measured on a
balance

Time
Time is the interval
between two events
 SI unit is the second
(s)

Temperature
For scientific work
Temp. is measured
in Celsius (oC)
 Freezing point is 0oC
and boiling is 100oC
 SI unit is Kelvin (K)
 Zero Kelvin is
coldest possible
point..That is equal
to - 273 o C)

Temperature Conversions
Volume
Volume is the amount of space occupied
by an object
 Solid object – measure length, width, &
height – multiply all three together and
units will be cubed (ex: cm3 )
 Liquid – use ml
 The conversion is 1mL = 1cm3

Density
Density is mass per unit of volume
 D = m/v
 Use a derived unit – a unit obtained by
combining SI units
 Example: mass is 10g and volume is 2cm3
 Answer: 5 g/cm3

SI Units

REMEMBER…any time you are measuring
ALWAYS try to get at least one decimal place
PASSED the unit used on device!
Ex: 3.5 m or cm…not just 3 or not 3 ½
m…or it could even be 3.52
 ALWAYS-give units…every time!
 Lets practice…with a partner look at a ruler,
meter stick, graduated cylinder, and a
thermometer. How would you record the
measurement?

How to Construct a Graph!



1 Identify the variables
Independent Variable (controlled by the experimenter)
 Goes on the X axis (horizontal). Time is almost
ALWAYS the independent variable. Time doesn't
depend on anything in most experiments. But many
things depend on it. This would be on the bottom
section of a standard graph.
Dependent Variable (changes with the independent variable)
 Goes on the Y axis (vertical) These are usually on
the right side of the graph.
How to Construct a Graph!

2. Determine the variable range.



3. Determine the scale of the graph.



Determine a scale (the numerical value for each square) that
best fits the range of each variable.
Spread the graph to use MOST of the available space.
4. Number and label each axis.


Subtract the lowest data value from the highest data value.
Do each variable separately.
This tells what data the lines on your graph represent.
5. Plot the data points.

Plot each data value on the graph with a dot.
How to Construct a Graph!

6. Draw the graph.




Draw a curve or a line that best fits the data points
Most graphs of experimental data are not drawn as "connectthe-dots".
However, occasionally we will do some that are connect the
dots..but we hope to see these represent a CURVE!
7. Title the graph.


Your title should clearly tell what the graph is about. This does
NOT need to be a full sentence long!
If your graph has more than one set of data, provide a "key" to
identify the different lines.
Inference
An inference is a logical interpretation
based on prior knowledge or experience.
 Ex: When testing a large body of water,
you take samples to test and them infer
your results to the entire body of water!

Inference…Line of Best Fit
The 'line of best fit' goes roughly through
the middle of all the scatter points on a
graph. The closer the points are to the line
of best fit the stronger the correlation is
Circle (Pie) Graph

A circle graph shows
percentages of a
whole
Line Graph

A line graph shows
trends of how data
changes over time
Bar Graph

90
80
70
60
50
East
40
West
North
30
20
10
0
1st Qtr
2nd Qtr
3rd Qtr
4th Qtr
A bar graph is used
to compare
information collected
by counting
Lab Reports
Any time you perform an “official” experiment
you will be required to write a lab report!
 The style of this report may vary from teacher to
teacher… but the basics will remain the same.
You must accurately follow the steps of the
scientific method, be able to explain all parts of
your experiment, show numerical data, and
state all findings.
 This must be done using complete sentences,
accurate grammar, and done neatly.


Six Steps to Wonderful Graphs