Intro Notes
Science – seeks to understand the world around us (Curiosity)
Physics = study of matter and energy and the relationships between them
Chemistry = the study of the composition, structure and properties of matter, and the reactions that change these
Scientific Method - the process science uses to systematically explore our world.
It develops and assures consistency from one experiment to the next, and one scientist to another.
It allows scientists to double-check each other.
If they doubt the results of an experiment, they can repeat it for themselves.
The generals steps are………
Question – anything that you want to answer or know
(Why is the grass green?)
Research – try to find the answer in previous materials. Look the answer up, don’t just experiment for
the heck of it. Maybe someone has already figured it out.
(You’ll find details on chlorophyll etc….)
Hypothesis – after you have researched the question, if you still don’t have an answer, make an educated
guess. It doesn’t have to be right, it just has to be testable
(Somehow I missed the explanation on chlorophyll, but I did find that green paint makes things
green. So…..I think grass is green because it is painted green. A valid, testable hypothesis)
Experiment – a process that can test, prove, or disprove your hypothesis and answer your question
Control = the part(s) of the experiment that is kept consistent from one version to the next
Variable = the single part of the experiment that is changed from one version to the next to
study its effects
(I decide to test the biggest nicest plot of grass I can find…..the football field. And it just so
happens I test it during football season. Unbeknownst to me I pick a spot on the field where
there was a mistake painting the lines, and someone corrected it with green paint.)
Analyze Data – take observations and measurements during the experiment, and record them. Decipher
what they mean.
(I find a plot of grass and I observe that this grass is green. The grass has green pain on it)
Conclusion – Using your data, decide if the experiment answered your question, and proved or disproved
your hypothesis
(Therefore I decide that grass is green because it is painted green. My hypothesis was right)
Repeat – Do it Again, and again… THE MOST IMPORTANT STEP
(Of course grass isn’t green because its painted green, but my experiment found that it was.
That’s why its important to repeat. To eliminate mistakes)
Theory – A hypothesis that has a repeated, consistent result of experimentation can become a theory.
Most things in science are not seen. They must be explained. Meaning there is no way to be 100% positive.
We only have a body of experiments and data that explain something, and are currently not “disproven”
Ex:: Atomic Theory or Theory of Evolution
Law – this is an observable aspect of our world. We can see it, and it is consistent.
It does not seek to explain anything, it is just an infallible observation of our world
A Theory cannot become a Law
Ex: Gravity or Law of Conservation of Energy
Fact – A currently accepted “truth” in science, although that truth is never final. It can and does change
A seriously debated, and not completely agreed upon concept. (String Theory etc…)
Essentially a Law can be “fact”, but theories technically shouldn’t be, but frequently are called “fact”
Bias – preference for one result or finding over another (Heisenberg Uncertainty Principle says it is unavoidable)
Safety is always a concern in a science classroom
The number one rule of lab safety is listen to the teacher’s instructions.
Always notify the teacher of anything that happens in a lab, especially accidents
Know where all the safety equipment in the room is
Measurement is the way that scientists ensure numerical consistency from one experiment to the next.
Measurement and Math are not the same thing.
Is 500 a lot? Is 1,000,000 a lot? Is 0.0001 a lot?
The best answer is it depends.
Is 500 pennies a lot of money? Is 1,000,000 grains of sand a lot? Is 0.0001% of the ocean’s water a lot?
Each has a definite answer.
The use of a “unit” is the best way to develop consistency in a measurement and differ from Mathematics
Gallons, pounds, atomic mass units, feet, dollars, days, hours all of these are units and convey meaning
Metric System – the most consistent and easiest of the measuring systems (meaning the best set of “units”)
It is base 10, the conversion is always a multiple of 10 (Why is it base 10? Why not base 12?)
Length = Meter (m)
Time = seconds (s)
Mass = Gram (g)
Volume = liter (L)
Uses a consistent set of prefixes with fixed values
Micro ()
milli (m)
centi (c)
Millionth
thousandth
hundredth
Kilo (k)
thousand
Mega (M)
million
Giga (G)
billion
Combine different prefixes to produce the desired or appropriate measurement
Microgram (g) = light object or Gigaliter (GL) = lots of liquid
Significant Figures = Some measuring devices are better than others. Significant figures are the method science uses to
indicate how “good” of an instrument you used, and therefore how good a measurement is.
A broomstick can measure length, but a meter stick is a better device.
It has more markings on it. Therefore you will get more “numbers” from using it
A person might be 1.5 “broomsticks” tall, or they could be 1.763m tall. (a better measurement)
The number of Sig Figs on an instrument is determined by its markings, or the digital places it can account for.
If an object that is being measured falls in between markings, you “guess” the last number and record it
When performing calculations with Sig Figs there are rules to follow:
ADDITION/SUBTRACTION = ANSWER MUST END IN THE SAME DECIMAL PLACE AS
THE LEAST PRECISE MEASUREMENT
3.86m + 4.2m + 11.510m = 19.570  19.6m
MULTIPLICATION/DIVISION = ANSWER HAS SAME TOTAL NUMBER OF DIGITS AS THE
LEAST PRECISE MEASUREMENT
409.2km / 11.4L = 35.895  35.9km/L
ALL INTEGERS ARE SIGNIFICANT
ZEROES ARE “TRICKY” =
If a measurement has a decimal point, start on the left and every number after the first integer is significant
If a measurement doesn’t have a decimal point, start on the right and every number after the first integer is signifi
1500.00 = 6
0.0001500 = 4
15000 = 2
15.001 = 5
Scientific Notation is the technique used to write really “big” numbers or really “small” numbers with only a few Sig Figs
You can only have 2 Sig Figs
125,000,000 = 1.3 x 106
0.00000235 = 2.4 x 10 -6
Precision – the measured results are reproduceable. They are consistent with each new attempt to measure
Accuracy – the measured results are “correct”, like a bullseye. They are consistent with an expected value
Complex units or measurements For example Density = mass divided by volume - typically grams per mL or cm3
Convert to grams and mL or cc and then divide to lowest terms
Density is a ratio, it is not how heavy something is