WELCOME TO THE LAB!!
INFORMATION
• Go over Syllabus (brief)
• Go over MICROWORLDS (brief)
– Two entries due by end of 2nd lab (week 2).
– Two entries due by end of 4th lab (week 4).
– These 4 & 6 additional by the end of lab 10.
– Samples that may be done today include pond
water and algae. Do not use oil today.
– Will have some time at the end of most labs.
LAB SAFETY - it’s mostly common sense:
• THINK ABOUT WHAT YOU ARE DOING BEFORE YOU
DO IT!!
• THINK ABOUT THE CONSEQUENCES!!
• LISTEN TO SPECIAL INSTRUCTIONS!!
• Go over safety/disposal stuff.
Prelabs (found on my web site):
• DO/COLLECT: Pre-lab #1.
• Normally done as homework & turned in at the start
of the lab. Prelab2 due at the start of the next lab.
Lab 1: The Metric System and the
Scientific Method
Two Approaches to Science
DISCOVERY SCIENCE
• No experiments
• Based on observations
• Inductive reasoning –
general principles derived
from large number of
specific observations
5
EXAMPLE: All living things are
composed of cells
Two Approaches to Science
HYPOTHESIS-BASED SCIENCE
• Involves carefully planned experiments
• Based on observations
• Deductive reasoning – takes a general
statement and extrapolates specific results we
would expect
Experimental Design
VARIABLES: things that
might change during the
experiment
• INDEPENDENT VARIABLE:
what you are changing in
the experiment (what
you’re testing)
• DEPENDENT VARIABLE:
what you are measuring
• CONSTANT VARIABLES:
things that are the same
between your groups
The DEPENDENT VARIABLE
depends
on the INDEPENDENT VARIABLE
Experimental Design – Controlled
Experiments
You generally have two groups:
1. CONTROL GROUP (CONTROL TREATMENT):
The group you are going to compare to; the
one you don’t do anything to
2. EXPERIMENTAL GROUP: The group(s) on
which you are testing something
Controlled Experiment
Control Group
Experimental Group
9
Only once?
• How many times should
you do an experiment?
10
Sampling Error
•
•
•
•
Draw 1 jelly bean?
Draw 10 beans?
Draw 100 beans?
Draw all the beans?
• SAMPLE SIZE: The
number of samples, the
more the better
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Scientific Notation and the Metric
System – Appendix A
• SCIENTIFIC NOTATION: More compact form of
a very large or very small number
• The distance to the Sun's nearest neighbor
Alpha Centauri is greater than
10,000,000,000,000,000 m.
Tools for Scientific Inquiry: Scientific
Notation
• Tells you how many times you must multiply
or divide by 10 to get the number
• A number x 10B
• The distance to the Sun's nearest neighbor
Alpha Centauri is greater than
1 x 1016m.
Tools for Scientific Inquiry: Scientific
Notation
• 1 x 1016 positive number = multiply by 10
10000000000000000
• 1 x 10-16m negative number = divide by 10
0.0000000000000001
Tools for Scientific Inquiry: Scientific
Notation
• MULTIPLICATION: Add the exponents
EX: (2 x 104)(3 x 105) = 6 x 109
20000*300000 = 6000000000
• DIVISION: Subtract the exponents
EX: (6 x 109) / (3 x 105) = 2 x 104
6000000000 / 300000 = 20000
Tools for Scientific Inquiry: The Metric
System
Metric System
• Science uses the metric system.
• The metric units are:
– meter for distance (measurement from one point to
another)
– liter for volume (ie, the space that 1 liter of water
occupies)
– gram for mass (weight),
– and degree Celsius for temperature.
• metric units do not advance like English: grain,
ounce, pound, ton
• they advance using prefixes & powers of ten
Metric how to use
• Not covered well in the manual, it is all
about powers of TEN
Metric Prefix
Meaning
kilo (kilometer, kilogram)
1000
meter, liter, gram
1
centi (centimeter, centiliter,
centigram)
1x10-2 (1/100 or 0.01)
milli (milliliter)
1x10-3
micro (micrometer)
1X10-6 (distance in
microscopes)
nano (nanometer)
1X10-9 (distance in electron
microscopes)
other prefixes are not commonly used
giga is used only in gigabytes & in Back To
The Future (1.21 jig-ă-wăts)
•
•
Another way to use metrics is to simply move the decimal to the
left when going up the steps and move the decimal to the right
when going down the steps.
For example, when converting from 9.9 kilograms to grams we
are going down 3 steps, so move the decimal three places right
or 9.9000 kg = 9900.0 grams
Metric System
Metric units are convertible.
• 1 cubic centimeter (or 1 cc) of water is equal to
1 milliliter (ml) which is equal to 1 gram of water
at sea level (& 1 BTU rises 1 cc 1°C).
• This does not work if water is not the material
of study!
Basic Metric Measurements
• You will measure water in a
cylinder, tends to stick to the
sides, especially with glass.
• This makes the meniscus,
the boundary between the
air and the water, curved.
• The correct way to read it is
to read it from the bottom of
the meniscus!
Converting Units
• Set up equations to cancel out units
200 m = cm
200 m * 1 x 102 cm = 20000 cm = 2 x 104 cm
1m
•THINK ABOUT YOUR ANSWER: Should there be
more cm than m? Should there be fewer?
•DOES YOUR ANSWER MAKE SENSE??
Practice Question
250 cm =
• Meters?
• Millimeters?
Measurements
Accurate
• How close is the
measurement to the true
value?
Precise
• How consistently can a
measurement be
reproduced?
Measurements
• Use a measuring tool that is close to the measurement you
want to make
For example, you would want to
measure an ice cream bar in
grams and an elephant in
kilograms and not vc. vs.
Lab:
• Read the information in the lab
• Practice measuring with a pipette, graduated
cylinder, balance, ruler/meter stick
• Be able to answer the questions at the end of
the lab in preparation for the quiz next week!
Lab: Black Box Experiment
• Identify what is contained in your box without
peeking!
• Use what is available to you in the lab and the
scientific method!
• Fill in the Black Box Experiment Data Sheet in the lab
and write your estimate
• Check it with me (if incorrect, try making a 2nd and
3rd experiment)
• When done, you may work on Microworlds (w/o
using oil!)
What you’re responsible for
• I AM giving a quiz on the lab next week
• Questions for the quiz will be pulled from the
lab and the study guide. Most labs have
questions at the end, I suggest you DO THEM!
• Lab1 and prelab2 will be turned in at the start
of lab2. Other than laba 1 & 10, the labs will
not normally be turned in.