Transcript The Scientific Method

Lab Safety and the
Scientific Method
Virginia Standard of Learning BIO.1a-m
BIO SOL: 1 a-m
The student will plan and conduct investigations in which:
• observations of living organisms are recorded in the
lab and in the field;
• hypotheses are formulated based on direct
observations and information from scientific literature;
• variables are defined and investigations are designed
to test hypotheses;
• graphing and arithmetic calculations are used as tools
in data analysis;
• conclusions are formed based on recorded quantitative
and qualitative data;
• sources of error inherent in experimental design are
identified and discussed;
BIO SOL: 1 a-m
The student will plan and conduct investigations in which:
• validity of data is determined;
• chemicals and equipment are used in a safe manner;
• appropriate technology including computers, graphing
calculators, and probeware, is used for gathering and
analyzing data and communicating results;
• research utilizes scientific literature;
• differentiation is made between a scientific hypothesis
and theory;
• alternative scientific explanations and models are
recognized and analyzed; and
• a scientific viewpoint is constructed and defended (the
nature of science).
Lab Safety
• Listen to instructions of your
__________.
• Work safely and cautiously
• Tie back hair, fasten loose clothing,
and secure dangling jewelry
• Do not taste and touch chemical
• No playing around in the laboratory
• Know the location of safety
equipment & fire evacuation routes
• Use safety wear when necessary
Equipment you MUST know!
• All parts of the
____________.
• Microscope slides
and cover slips
• Graduated Cylinder
• Petri dishes
Graduated Cylinder – The meniscus
Jan consistently read the volume of liquids as
shown. How would this practice impact her work?
a) Her measurements would be very accurate
b) Her measurements would be too high.
c) Her measurements would lack precision.
d) Her measurements would be too low for less
dense liquids.
The petri dish
SOL question
In the lab setup pictured below, a student is trying to
determine the effect of pollutants on the growth of three
groups of seeds. The results will not be valid because
the experiment does not have a
The Scientific Method
• An organized way to solve a
problem through experimentation &
______________.
The 6 Steps of the Scientific Method
1. State the
__________
• Form a question about a specific
event or reaction
EX: Mouthwash kills bacteria.
Which brand works best?
2. Collect Information
• Research the problem
• Make ____________
EX: Read the labels of 3
common brands of mouthwash
and see which has the most
antiseptic (germ-killing)
ingredients.
Observation vs Inference
• Observationsmade with the
___________
–
–
–
–
–
____________
____________
____________
____________
_____________
• ___________ – a
conclusion based on
________ and
________.
– Ex: Jimmy said he
was not feeling well
yesterday. He did not
come to school today.
I infer that he did not
come to school
because he is sick.
3. Form a hypothesis
• Make an educated guess based on
your _______________________.
A hypothesis can be recognized by
an “_____, ________” statement.
EX: If Listerine has more antiseptic
ingredients than Scope or Wal-Mart brand,
then it will kill more bacteria.
4. Design an Experiment
• Devise a way to test your hypothesis.
Create a ____________ experiment.
• A controlled experiment MUST have
__ groups.
CONTROL GROUP: all
conditions remain the ______
EXPERIMENTAL GROUP: only
the condition that you are
testing for is _________.
ONLY ____ condition is
changed!
• Establish the variables for your
_______________.
_______________ VARIABLE: the
variable that is changed, manipulated
_______________ VARIABLE: the
change caused by the manipulation
of the independent variable
• _______________- variables that
will be kept the __________ in the
_____________ group and the
__________________ group.
– Ex: The control group will receive 10ml
of water and each experimental group
will receive 10ml of each mouthwash.
• Trials
– __________________ groups that are
exposed to the same conditions in an
experiment.
– Minimum of _____ trials
• (the experiment must be done a minimum
of 3 times )
Mouthwash Experiment
Control Group
-no mouthwash
Petri dish
Bacteria grown
from swab
Listerine
Experimental
Group
Scope
Wal-Mart
brand
Mouthwash Experiment
INDEPENDENT VARIABLE:
_________________
DEPENDENT VARIABLE:
_______________________
5. Collect & Analyze Data
• Run the experiment & collect the
_________.
• 2 Types of Data
___________ITATIVE: numerical
data, deals with specific quantities,
usually in the form of a graph or chart
__________ITATIVE: descriptive
data, describes how something
looks, smells, sounds, or feels; deals
with qualities
How do scientist measure
quantitative data?
• All scientist use the ______ (metric)
system .
– Based on units of _________
– Most countries use the metric system
• Standard Units of Measure
– Volume- ___________
– Mass- ____________
– Distance- __________
How is data recorded?
• Charts
– Used for qualitative and quantitative
data
• Graphs
– Type of graph used is dependent on
the type of data collected.
How to Graph
• Identify your variables/Label your
axis
– __ goes on the _________ (horizontal)
– ___ goes on the _________ (vertical)
• Determine the range and scale
• Plot your points
• Title graph
Types of Graphs
•
•
•
•
•
Pie Chart
Bar Graph
Histogram
Line Graph
Scatter Plot
QUALITATIVE EX: The control group and
the Wal-Mart brand have a strong smell;
the Listerine & Scope don’t smell as bad.
QUANITATIVE EX:
Area of Inhibition for Mouthwash Brands
5 min
10 min
15 min
20 min
Control
Listerine Scope
Wal-Mart
0 mm
0 mm
0 mm
0 mm
3 mm
4 mm
6 mm
8 mm
1 mm
3 mm
4 mm
4 mm
2 mm
3 mm
5 mm
6 mm
6. Draw Conclusions
• Determine from the data collected if the
hypothesis was correct or incorrect
• _______________________
EX: Listerine did kill more bacteria
than the other brands because it had
more antiseptic ingredients.
The 7th Step
• __________/_________ your
findings
– Scientists often publish their findings in
scientific journals/magazines, peerreviewed journals
Let’s Review!
________________
• ____________- a possible explanation
to a question based on information the
scientist has already gathered
- If experiments show a hypothesis to be
correct, other scientists may accept it as
support for a scientific theory.
EX: Plants obtain their energy from the
sun.
____________
• ________________ Theory- a ________
statement of why things work based on
hypotheses that have been ____________
many times
• _______________ Generation Theory
stated that living things can arise from
non-living matter. ____________ _______
believed that maggots formed naturally
from rotting meat.
Sometimes theories are __________
_________ __________ was one of the
scientists that helped to confirm that the
Spontaneous Generation Theory by
Francesco Redi was wrong!
Eyepiece
Body Tube
Revolving Nosepiece
Objective Lens
Stage
Clips
Diaphragm
Light
Arm
Stage
Coarse Focus
Fine Focus
Base
Total Magnification Formula
Objective lens
Scanning 4X
Power
Low
10X
Power
High
40X
Power
Ocular
10X
10X
10X
Total
Magnification
• Switch to ______ power
• Switch to ______ power objective
• Do _____ use the Coarse Focusing
Knob
• Use the Fine Focus Knob to bring
the slide
What can you find on your slide?
Equipment - MICROSCOPE
HOW TO MAKE A WET MOUNT SLIDE
Use a temporary microscope slide
and a ________________.
Specimens will appear
with a ________ image
Wet mount SOL Question
• The picture shows a coverslip
correctly being lowered onto a slide.
This method is used because it —