Ch 1.3
Scientific Methods
Investigation & Experimentation Standards
1: a, b, c, d, e & g, j, k, l, & n
Scientific progress is made by
asking meaningful questions and
conducting careful
investigations. As a basis for
understanding this concept and
addressing the content
students should develop their
own questions and perform
investigations. Students will:
a.
b.
c.
d.
e.
f.
g.
h.
Select and use appropriate tools and technology (such
as computer-linked probes, spreadsheets, and
graphing calculators) to perform tests, collect data,
analyze relationships, and display data.
Identify and communicate sources of unavoidable
experimental error.
Identify possible reasons for inconsistent results, such
as sources of error or uncontrolled conditions.
Formulate explanations by using logic and evidence.
Solve scientific problems by using quadratic equations
and simple trigonometric, exponential, and logarithmic
functions.
Distinguish between hypothesis and theory as
scientific terms.
Recognize the usefulness and limitations of models
and theories as scientific representations of reality.
h. Read and interpret topographic and geologic maps.
i. Analyze the locations, sequences, or time intervals that are
characteristic of natural phenomena (e.g., relative ages of rocks,
locations of planets over time, and succession of species in an
ecosystem).
j. Recognize the issues of statistical variability and the need for controlled
tests.
k. Recognize the cumulative nature of scientific evidence.
l. Analyze situations and solve problems that require combining and
applying concepts from more than one area of science.
m. Investigate a science-based societal issue by researching the
literature, analyzing data, and communicating the findings. Examples of
issues include irradiation of food, cloning of animals by somatic cell
nuclear transfer, choice of energy sources, and land and water use
decisions in California.
n. Know that when an observation does not agree with an accepted
scientific theory, the observation is sometimes mistaken or fraudulent
(e.g., the Piltdown Man fossil or unidentified flying objects) and that the
theory is sometimes wrong (e.g., the Ptolemaic model of the movement of
the Sun, Moon, and planets).
Scientific Inquiry… a search for information and
explanation often focusing on specific questions.
 TWO MAIN FORMS OF INQUIRY:
 1. Discovery Science
 describes natural structures and processes as accurately as possible
through careful observation and analysis of data. Conclusions based on
logic… “inductive reasoning”.
 Ex. microscope observations led to the CELL THEORY
 2. Hypothesis-Based Science
 Process of inquiry that includes repeatable observations and testable
hypotheses… “deductive reasoning” if… then statement.
 Science “to know” is limited to those structures and processes we can observe
and measure.
 Science can not answer questions like
“Why are we here?” … this is why the humanities are so important.
Applying hypothetico-deductive reasoning to a campground problem
Steps of the Scientific Method
1.
Observation- use senses to perceive object or events
2.
Ask Questions-
3.
Collect & organize data- longest phase of investigation



use specific tools ex. microscope to observe directly or indirectly (voltmeter)
quantitative (measured in numbers)
Sampling (a small part represents an entire population)
Hypothesize- a testable explanation that explains the observations
and predicts the outcome
4.


Prediction posed as “if___ then___” statement.
Inferences use logic and prior knowledge to make sense of the data
collected and predict the result of a well-designed experiment.
5.
Experiment- testing a hypothesis under controlled conditionscomparison between control group & experimental group
6.
Draw conclusions
7.
Ask new questions
8.
Design new experiment (repeat & refine)
How to write a Lab Report:
(this mirrors the scientific method )
1.
Title
2.
Introduction (observations, background info, purpose of
experiment)
3.
Hypothesis (is a prediction)
4.
Materials & Methods (explain the experiment)
5.
Results (tables, graphs- quantitative/qualitative)
6.
Discussion (analysis of results, misatkes?, conclusion,
next experiment)
What are the elements of an
excellent experiment???
What are the elements of an
excellent experiment???
1.
Control the variables (variables are any factors influencing the
results of your experiment- keep them CONSTANT).
2.
Have a large sample size of test subjects &/OR repeat your
experiment to counter unavoidable experimental error.
3.
Have a control group to compare your experimental group to so
you see magnitude of the results.
4.
Change only ONE variable between these groups while holding
all others constant. =‘s the INDEPENDENT VARIABLE
5.
Obtain quantitative data (when possible) and use appropriate
tools for measurement

6.
Ex. pH meter, volt meter, microscope, ruler, scale, geiger counter.
Organize collected data- measured results = DEPENDENT
VARIABLE in a data table then show as a graph.
A controlled experiment is a comparison of two or
more groups with only one difference in variables
between the groups when you set up your
experiment.
CONTROL GROUP
1.
2.
3.
4.
5.
6.
Soil
Sunlight
H2O
CO2
O2
Real trees
EXPERIMENTAL GROUP
1.
2.
3.
4.
5.
6.
Soil
Sunlight
H2O
CO2
O2
Artificial trees
The difference between the groups is called
the INDEPENDENT VARIABLE
 IT IS THE AGENT OF CAUSE IN YOUR EXPERIMENT
 The difference between your control group and
experimental group(s).
 What you are testing.
 Plotted along the X-axis
 Ex. artificial plant
Now you can run a great experiment!!!
But how will you know the results???
The measured result of your experiment is the
DEPENDENT VARIABLE
 THE EFFECT OF YOUR EXPERIMENT
 The observable result of your experiment.
 Plotted on the Y-axis.
 Dependent variables are caused by the independent
variable.
 You take some sort of measurement and record it.
 Ex. stem height in centimeters
TITLE: A comparison of a car’s value related to its’ mileage
Y axis
(dollars)
X axis
(miles)
When is a line graph appropriate?
When is a bar graph appropriate???
What’s the deal with this double bar graph?
Why the pie chart?
Display parts of a whole.
ANALYSIS
• ANALYSIS:
• What were the results and what do they
•
•
•
•
mean?
Was data good or bad?
Were mistakes made?
Make a conclusion- does the data
support or refute the hypothesis? What
if neither??? Inconclusive…
What should be done next? Design your
next experiment.
DRAWING CONCLUSIONS
1.
INFERENCE- a conclusion made on the collection of facts not on direct
observations. = hypothesis
ie. Owl pellets let you know what it ate.
2.
MODEL- explanation supported by data.
ie. Atom structure or structure of the universe
3.
LAW- analytical statement empirically provable using math- has a constant.
Considered universal and invariable facts.
ie. Gas Laws, Kepler’s Laws of Planetary Motion, Law of Conservation of Energy,
Newton’s Law of Universal Gravity
3. THEORY- broad, comprehensive statement of what is thought to be true.
*few theories exist…they are supported by tremendous amounts of evidence… ties
together several related hypothesis and may incorporate one or more laws.
ie. Relativity, Natural Selection, Germ Theory
Theories can be proven wrong, so can Laws.
TOP 6 Disproved Theories:
Static or unchanging Universe
Spontaneous generation
Expanding
Earth
Phlogiston
Theory
The Blank
Slate
Theory
Martian
Canals
www.toptenz.net/top-10-most-famous-scientific-theories-that-turned-out-to-be-wrong.php
6 THEORIES YOU MAY HAVE HEARD
OF:
The Big Bang Theory
Theory of Natural
Selection
Cell Theory
Plate
Tectonics
Theory of
General
Relativity
String
Theory
Standards 1 a, b, c, d, e & g
a.
b.
c.
d.
e.
g.
Select and use appropriate tools and technology (such as
computer-linked probes-pH meter, spreadsheets, and
graphing calculators) to perform tests, collect data, analyze
relationships, and display data.
Identify and communicate sources of unavoidable
experimental error.
Identify possible reasons for inconsistent results, such as
sources of error or uncontrolled conditions.
Formulate explanations by using logic and evidence.
Distinguish between hypothesis and theory as scientific
terms.
Recognize the usefulness and limitations of models and
theories as scientific representations of reality.
Standards 1 j, k, l, & n
j. Recognize the issues of statistical variability and the need
for controlled tests.
k. Recognize the cumulative nature of scientific evidence.
l. Analyze situations and solve problems that require
combining and applying concepts from more than one area
of science.
n. Know that when an observation does not agree with an
accepted scientific theory, the observation is sometimes
mistaken or fraudulent (e.g., the Piltdown Man fossil or
unidentified flying objects) and that the theory is sometimes
wrong (e.g., the Ptolemaic model of the movement of the
Sun, Moon, and planets).
THE FIRE LAB: answers
PART I: #1-3
 Light emitted from candle, flame moving
 Orange flame on match
 Blue flame toward wick of candle
 Flame moves w/ air.
 Wick is black.
PART II: #1 & 2
 Match burns shorter/ temperature is hotter
 The ignition of match is more volatile
 Candle burns longer/ temperature is not as hot.
 Flame is pale on candle and darker (more orange) on
the match.
#3 & 4
 Birthday candle flame taller, brighter burning, burns
more quickly, wax can drip down.
 Votive candle has a shorter flame as the wax can’t
escape and pools at base of wick.
 The higher the surface area, lower burning (wax is
contained) = slows the burning process, less wick
exposed.
 Black around the wick is CARBON.
#5
 Beaker: flame to the bottom of the beaker: glass
turns black.
#8
 Physical & Chemical change difference is
that the molecules remain the same just
change their state of matter (solid, liquid,
gas) where as a chemical change breaks
bonds and forms new bonds creating new
molecules.
 Black soot is carbon = chemical change of
the wax.
 the wax from solid to liquid to gas = physical
change
#9
 Oxidation = burning sugar in our bodies to get
energy.
 Cell respiration (in mitochondria)
PART III: 1 a-d & 2
OBSERVATIONS
 Flame gets smaller and flame goes out
 Water rises in the beaker (higher than level outside the beaker.)
INFERENCES/HYPOTHESIS
 Heat up the gas molecules and the gases expand.
 Flame goes out when there is no oxygen left.
 When the flame goes out the molecules cool down and contract pulling
water into the glass beaker.
LIGHT TWO CANDLES
 Will happen faster??? Two flames use up the oxygen faster.
HOW TO VIEW A FLAME…
 More complete burn of gas (flame turns blue)
releases the most heat.
 More incomplete burn of gas (flame turns
orange/yellow) is good for giving off light.
 Carbon monoxide, which is toxic, is given off w/ an
incomplete burn. SCARY.
PART IV
#2
1) Wax + O2 -> CO2 + H2O + Energy (FULL BURN)
 Blue flame = most complete burn… means more oxygen getting
in (at bottom).
2) Wax + O2 -> CO + H2O + Energy (MIDDLE burn)
 Orange or dark part of flame in the middle
3) Wax + O2 -> C + H2O + Energy (most incomplete)
 Smoky part of flame at top
#2: What is the significance of this
information????
 Candles used to see (light energy) orange/yellow.
 Burning for heating energy- blue… more complete
burn.
 Burning sugar in your body…
 OXIDATION = energy formation in our bodies- sugar
is burning to make energy. This is why you need
oxygen to live!!!!
Steps of the Scientific Method
1.
Observation- use senses to perceive object or events.
2.
Ask Questions
3.
Collect & organize data- sample or quantitative
4.
Hypothesize- a testable explanation
5.
Experiment- testing a hypothesis under controlled
conditions
6.
Draw conclusions
7.
Ask new questions
8.
Design new experiment
MOUTHWASH LAB
Observations:
 People have stinky breath
 People use “mouthwash” to prevent bad breath
and to keep their teeth healthy.
Ask Questions:
 What is making their mouths stinky? What are
you protecting teeth from?
 Which mouthwash brand is the best one? Cost,
ingredients, packaging, endorsements
3. Collect and organize data
1.
Bacteria cause the bad breath and tooth decay.
•
Are: single-celled, prokaryotic, micro-organisms
that reproduce by binary fission.
•
1st life forms that evolved 3.5 billion years ago
•
Ex. One bacterium can reproduce every 20
minutes. Thus millions can exist from the
reproduction of just one with in 24 hours.
•
Some are good, some cause tooth decay (secrete
acids that are corrosive to enamel).
•
Their dying bodies and waste products they
secrete are what make your mouth stink.
Bacteria are alive. Need water and
nutrients to grow. Reproduce by Binary
Fission to form Colonies that are visible
w/out a microscope.
BINARY FISSION
PETRI DISH WITH NUTRIENT AGAR
SHOWING SEVERAL DIFFERENT
BACTERIAL COLONIES
MOUTHWASH INFORMATION
 Target Scope $2.09
 Crest Blue $4.19
 Listerine Purple $3.44
 Listerine Yellow $3.99
 You might want to
check the ingredients
yourself.
Define mouthwash.
HYPOTHESIS
 Based on the collected information, create not only
your best guess for which one is best- but create it as
an if then statement.
 I predict that _______ is the best mouthwash. If it is
then ________ will happen.
DESIGN YOUR EXPERIMENT
 Do this today.
 Conduct the experiment today. Draw exactly what your petri dish looks like today and
mark the exact time and date.
 We’ll check the results next week.
MATERIALS AVAILABLE TO EACH GROUP OF 4:
 Petri dish with nutrient agar (it is delicate, don’t break the agar when spreading your
bacteria on the plate.)
 1 Q-Tip (to get your bacteria sample)
 1 sharpie marker (to write on your petri dish)
 Paper soaked in various mouthwash brands & water.
 Forceps (tweezers) for moving the paper discs soaked in solutions.
 Parafilm to seal the petri dish lid to the plate.
RESULTS
 NEXT CLASS WE WILL LOOK FOR AND MEASURE the
absence of BACTERIAL COLONIES.
 RING OF INHIBITION- forcefield / break in the lawn.
Ring of Inhibition=
Dependent variable