Technical Science
Scientific Tools and Methods
Making Observations
●
In this section you will …
– Define science– Differentiate between qualitative and quantitative observations
– Explain why a measurement must include both a number and a unit
– Describe the purpose of a standard
What is Science?
● There have been many definitions for this word
over the years. You may have a few of your own. You may think of science as an experiment, as a big book of facts, or as a collection of theories. All of these answers have some truth to them but we are going to use a slightly broader definition.
● Science can be defined as: The process of discovering how the world works.
1 of 5
What is Science?
● Notice the definition says, science is the process of discovering how the world works.
● It did not say that science is collection of facts and theories. While it is important to know some facts and theories, science is much more concerned with uncovering these concepts.
● This may seem like a minor point but you will see it is a very important distinction.
What is Science?
● The Earth is flat!
The Sun revolves around the Earth! The atom is indivisible!
● It wasn’t very long ago that people accepted these “facts”. They may sound silly now but these
theories were the result of the best scientific processes of the day.
● As discoveries were made, these ideas were modified, adjusted, or thrown out altogether.
What is Science?
● Facts and the theories will change.
● The process of questioning what is currently accepted and looking for the undiscovered is constant.
● This process is what pushes technology, science, and society forward.
What is Science?
● Take a minute and write your definition of Science. Once you have completed your definition click to check your work.
5 of 5
Α Science is the process of discovering how the
world works.
Qualitative & Quantitative
Observations
●
Before scientists can figure out how the
world works they must make accurate
observations about the world around them.
●
These observations can be divided into two
categories.
●
Qualitative or Quantitative observations
1 of 9
Qualitative & Quantitative
Observations
● Take any object you have with you and make as many observations as you can about it.
2 of 9
Α Most of the observations you made probably dealt
with the way the object looked.
q They may have described the shape, color, or size q They may have described the smell, taste, or texture
Qualitative & Quantitative
Observations
●
The observations just listed (shape, color,
texture, etc) are Qualitative observations.
●
Qualitative observations deal with the
properties or qualities of an object.
●
Qualitative observations are important
because they help us identify an object.
●
In other words, it is an object’s qualities that
tell us what the object is.
Qualitative & Quantitative
Observations
● Let’s say that I have an object in the bag.
● If I tell you the object is small, flat, round, and metallic…
● You could probably guess that the object is a coin.
Qualitative & Quantitative
Observations
●
The problem with qualitative observations is
that they aren’t very precise.
●
Qualitative observations don’t tell us
how
small,
how
colorful,
how
hard an object is.
●
To get this type of information, you need to
make Quantitative observations
Qualitative & Quantitative
Observations
●
Quantitative observations deal with the
amount or quantity of an object’s properties.
●
A quantitative observation can tell us how
heavy an object is; 5 pounds for example.
●
You could make quantitative observations
about an object’s length, volume, mass, etc.
– 2 inches, 3 gallons, or 400 grams are just a few examples of quantitative observations
Qualitative & Quantitative
Observations
●
Quantitative observations are also called
measurements
●
Quantitative observations or measurements
are important because they are exact while
qualitative observations can be imprecise.
– A dish of ice cream may be “big” to one person but “small” to another. If the weight were
measured there would be no question about the amount of ice cream.
Qualitative & Quantitative
Observations
● Decide whether the observations are qualitative or quantitative. When you are done click to check your answers.
8 of 9
Round 2 liters Hot Small
2.3 cm Brown 2 mm 3 grams
5 seconds Fast Solid 32° C
Qual Quant Qual Qual
Quant Qual Quant Quant
Qualitative & Quantitative
Observations
● Define Qualitative and Quantitative observations.
Qualitative =
Quantitative =
9 of 9
Α Qualitative observations are descriptions of the object’s properties or qualities.
A Quantitative observations are measured amounts or measurements.
Parts of a Measurement
●
Measurements describe an object’s
properties in very precise terms. They tell
how big, how heavy, how fast, etc.
– A sheet of paper may have a length of 11 inches
●
You can see that measurements are written
differently from qualitative observations.
●
Every measurement must have a
number
and an
unit
of measure.
1 of 4
Parts of a Measurement
● Measurements must have a number and a unit.
● If you were told a piece of paper measures 11, you would have no way of knowing if it were...
– 11 inches,
– 11 feet,
– or 11 miles
11
in 11
ft
11
miles
Parts of a Measurement
● Measurements must have a number and a unit.
● If you were told a piece of paper was measured in inches, you wouldn’t know if it were...
– 1 inch,
– 11 inches,
– or 111 inches
1
in 11 in
111
inches
Parts of a Measurement
● What are the two parts of measurement? Why is each part important?
4 of 4
Α Every measurement must have a number and a unit.
A The number tells how many pieces and the unit describes the size of a each piece.
What is a Standard?
● Use your pen or pencil to measure the length of the table. What is the length of table in pencils?
1 of 6
A The table is 5 pencils long.
What is a Standard?
●
When you make a measurement you
compare a property of an object to some
specific unit.
●
In the previous slide you compared the
length of a table to pencils. You found the
table was 5 pencils long.
●
This may seem foolish but years ago a unit
of length was the distance from the king’s
heel to his toe: “one foot”
What is a Standard?
● What is the problem with measuring in terms of pencils or the king’s foot?
3 of 6
What is a Standard?
●
You can see how much confusion would be
caused if everyone got different results after
measuring the same thing.
●
Imagine what would happen in trade where
things are sold by weight or length.
●
To eliminate this confusion, what we need
are units of measurement that are Standard.
What is a Standard?
● A standard is a unit of measure that is the same no matter where you go.
● A 10 K race is the same distance in...
– Wisconsin
– Brazil
– or China
5 of 6
What is a Standard?
● What is a standard? Give two reasons why they are important.
6 of 6
Α A standard is unit of measure that is the same everywhere you go.
Α Standards eliminate confusion by insuring that
measurements are consistent from person to person and from place to place.
Accuracy vs Precision
●
When you make a measurement it is often
necessary to determine how good that
measurement is.
●
Imagine a machine filling cans of soda. The
company wants to make sure that there are
exactly
12 ounces of soda in
every
can.
●
The company needs to gather information
about the accuracy and precision of the
filling machine.
1 of 9
Accuracy vs Precision
●
Accuracy and precision tell us how good a
measurement is.
●
The terms accuracy and precision often
cause trouble because we tend to use them
interchangeably. However, these words
have very different meanings.
●
Accuracy tells how close the measurement
is to the true value. Precision describes the
repeatability of the measurement.
Accuracy vs Precision
3 of 9
● A measurement is precise if it can be repeated and the same value is attained.
? Is the soda filling machine below precise?
Α This machine is not very
precise.
– It delivers a different
Accuracy vs Precision
4 of 9
● A measurement is accurate if it is close to the true value. This machine is supposed to deliver 12 oz.
? Is the soda filling machine below accurate?
Α This machine is not very
accurate either.
Accuracy vs Precision
5 of 9
● Is the soda filling machine below accurate and/or precise?
Α This machine is precise. – It delivers the same
amount of soda each time.
Α This machine is not
accurate.
Accuracy vs Precision
6 of 9
● Is the soda filling machine below accurate and/or precise?
Α This machine is precise. – It delivers the same
amount of soda each time.
Α This machine is accurate. – It is putting 12 oz in each
Accuracy vs Precision
7 of 9
● We said that this machine is accurate because it is delivering 12 oz of soda. But how do we know that exactly 12 oz is going into each can?
● The only way to check the accuracy of a measurement is compare it to a standard.
– Standards have known values
Accuracy vs Precision
● Define accuracy and precision
8 of 9
Α Accuracy describes how close a measurement is to the true value. You need a standard to determine
accuracy.
Accuracy vs Precision
● How could you tell if the scale in the produce department of the supermarket is accurate and precise.
9 of 9
Α The only way to check the accuracy of the scale is to use a standard. You need something of known weight. If you put a 1 pound package of butter on the scale and it reads 1 pound then the scale is accurate. The butter was used as a standard.
Α You could weigh a bunch of bananas three times. If you get the same value each time then the scale is precise. This doesn’t necessarily mean the scale is accurate.
