Unit 1
Scientific Method, Graphs, Metric
System, and Measurement
Physical Science

Physical science is the study of
 Matter, which is also known as
chemistry
Matter is anything that takes up space
Like animals, people, rocks, and air
 Energy, which is also known as physics
Energy is the ability to cause change
Like lightning, motion, and sound
What We Know in Science
A fact is something known to be true.
Facts can be gained by observation, or
using your senses.
 A theory is a logical explanation for events
which occur in nature.
 A scientific law is a theory that has been
tested many times and is generally
accepted as true.

Scientific Method


How do scientists investigate questions?
The scientific method is a system that
scientists use to solve problems
Scientific Method

The scientific method includes 7 steps
1.
2.
3.
4.
5.
6.
7.
Stating the problem
Gathering information on the problem
Forming a hypothesis
Performing experiments to test the
hypothesis
Recording and analyzing data
Stating a conclusion
Repeating the work
Scientific Method Activity
1.
2.
3.
Work with the person next to you. If you
are at a table by yourself, work with the
pair at the table joining yours.
Get 1 bag of m&m’s per group. (DO NOT
OPEN BAG YET)
Decide on one question you would like to
answer about your bag of m&m’s. Write
it down. (DO NOT OPEN BAG YET)
How many m&m’s are in a bag?
4. Guess what your answer might be
(hypothesize).

Hypothesis: A testable prediction used to
see how something works or to solve a
problem
(Glencoe Physical Science, p. 760)
How do we find out if our
hypothesis is correct?
5. Open your bag of m&m’s and count them!





Count how many of each color you have, too.
Data: Recorded observations and measurements
Data collection: Gathering information about our
hypotheses.
One way to gather data is through observation, which is
using your senses
We can also gather data by doing an experiment. An
experiment is a procedure for testing a hypothesis.
(Glencoe
Physical Science, p. 758)
Experiments
Experiments usually have a control,
which is a standard to compare your
results to.
 A constant is a factor that does not change
during the experiment.


In our experiment, the kind of candy we
looked at, plain m&m’s, stayed the same
Variables
Experiments have variables, which are the
factors being tested during the experiment.
 Experiments have independent and
dependent variables.

Independent variable – A factor that I, as the
experimenter, control.
 Dependent variable – A factor whose value
depends on the value of the independent
variable

Experiments

You can also have multiple trials, in which
you look at the same set of variables more
than once. In our case, we looked at lots
of bags of m&m’s.
What can we say about a big bag
of m&m’s?
Do we know for sure how many and what
colors are in the bag?
 Can we make a pretty good guess based
on what we know from the small bags?
 That is an inference – a conclusion or
guess based on evidence.

My Experiment

What if I wanted to know how your sleep
would affect your test grades?
Group 1 – Study 1 hour, sleep 8 hours, arrive
to take the test at 8:00 a.m.
 Group 2 – Study 1 hour, sleep 6 hours, arrive
to take the test at 8:00 a.m.
 Group 3 – Study 1 hour, sleep 4 hours, arrive
to take the test at 8:00 a.m.
 Group 4 – Study 1 hour, sleep 2 hours, arrive
to take the test at 8:00 a.m.

My Experiment
What would be a hypothesis for this experiment?
Which group might be a good control?
Which variable would be my independent variable?
Which variable would be my dependent variable?
What would be the variables I kept constant?
How could I do multiple trials?
How can we look at our data?
Use a graph
 A graph is a visual display of
information or data

Circle Graphs or Pie Charts

Used to show how a fixed quantity is
broken down into parts.

The circle represents the total and the
slices represent the parts.
Bar Graphs

Useful for comparing information collected
by counting.
9
8
7
6
5
Series1
4
Series2
Series3
3
2
1
0
1
2
3
4
5
Line Graphs

Used to show trends,
or how data changes
over time.
100
90
80
70
60
50
40
30
20
10
0
East
West
North
1st Qtr
2nd Qtr
3rd Qtr
4th Qtr
Designing an Experiment
The greater the amount of soap in a
soap and water mixture, the bigger
a soap bubble can be made.
 Design
an investigation to test this
hypothesis.
 Identify the variables
 What exactly will be changed? How
will it be changed?
 What exactly will be measured?
How will it be measured?
The farther a ball drops, the
farther it will bounce.
 Design
an investigation to test this
hypothesis.
 Identify the variables
 What exactly will be changed? How
will it be changed?
 What exactly will be measured?
How will it be measured?
Measurement
 Metric
System - System of
measurement used by scientists
 Also
known as the International
System of Units, abbreviated SI
 Based on the number 10
Length
 Length
is the distance between
two points
 The
SI base unit is the meter
(abbreviated m)
 May be measured with a meter stick
or a metric ruler
Measuring Length
 Start
the measurement at the 0cm
mark on the ruler or meter stick
 Read the length of the object to the
whole centimeter, then count the
tenths of a centimeter (or
millimeters) and add those in the
tenths place, estimate one more
digit in the hundredths place
Temperature
 Temperature
is a measurement of
how hot or cold something is
 Our
thermometers always read ºC
 Water freezes at 0ºC
 Water boils at 100ºC
 The celsius scale is divided into 100
equal divisions
 Read the thermometer to the nearest
degree or half degree
Measuring Temperature





Handle thermometers carefully
Place them on a paper towel on the table to
prevent rolling
Do NOT shake
Make sure that the bulb of the thermometer is
completely under the liquid being measured and
that the line on the thermometer is no longer
moving before reading
To take reading, make sure that your eye is at
the level of the liquid on the thermometer
Temperature
 The
SI unit for temperature is Kelvin
(abbreviated K)
 Zero
on the kelvin scale (0K) is absolute
zero, the coldest possible temperature
 We can find the temperature in Kelvin by
taking our temperature reading in ºC and
adding it to 273
25 ºC to K  273 + 25 =298K
Volume
 Volume
is the amount of space
occupied by an object
 The
SI base unit is the liter
(abbreviated L)
Measuring Volume
 Volumes
of many solid objects may
be calculated by measuring the
length, width, and height of the
object, then multiplying the numbers
together
V=LxWxH
Measuring Volume
V=LxWxH
V = 4cm x 3cm x 12 cm = 144 cm3
Measuring Volume
Liquid volumes should be measured with a
graduated cylinder (in mL)
 When reading a graduated cylinder, you have
to look at the graduated cylinder at eye level
 Read the bottom
of the meniscus,
the curve of the
liquid on the cylinder
 Read to the nearest unit
or half unit

Measuring Volume
• Volumes of irregular solid objects may
be determined by the displacement
method
• Put some water in a graduated cylinder
and record the volume
• Add the object to the graduated cylinder
• Record the new volume
• The difference between the new volume
and the original volume is the volume of
the object
Measuring Volume
Displacement Method:
• http://www.middleschoolchemistry.com/mul
timedia/chapter3/lesson2#water_displace
ment
Mass
• Mass is the amount of matter in
an object
• The standard unit of mass is the
kilogram (abbreviated kg)
• Our balances measure mass in
grams (g)
Measuring Mass
• Measure the mass of a solid using
a balance
• Balance may be digital or triple
beam
• Use a weigh “boat” to hold the solid
on the pan of the balance
Measuring Mass
• Triple beam balance
• Make sure all of the riders are on 0
• Place the boat on the pan
• Move the rider for the hundreds place
one notch at a time until the pointer
drops, then move the rider back one
notch. Make sure the rider is securely in
its notch
• Repeat this step with the rider for the
tens place and the rider for the ones
place
Measuring Mass
• Triple beam balance
• Now slide the rider for the tenths place
until the pointer swings an equal
distance on each side of the center mark
• Read that rider to the nearest tenth or
halfway between (0.05)
• When the pointer matches the center
mark, add up the masses shown on the
beams
Measuring Mass
• Digital balance
• Make sure the balance reads 0.0g
• If not, press the “Zero”button
• Measure the mass of the boat and
record it
• Add the solid to the boat
• Measure the mass of the boat and the
solid
• To find the mass of the solid, subtract the
mass of the boat from the mass of the
boat and the solid
Measuring Mass
• Measure the mass of a liquid using a
balance and a graduated cylinder
• First mass the empty graduated cylinder
• Add the liquid to the graduated cylinder
• Mass the liquid and the graduated
cylinder together
• To get the mass of the liquid, take the
mass of the liquid and graduated
cylinder and subtract the mass of the
graduated cylinder.
Measurement Lab
• 9 Stations
• Work in assigned groups
• Rotate through the stations in order,
going to station 1 after you finish
station 9
• Be sure to clean up each station and
put everything back the way you
found it before moving to the next one
Density
• Density is the mass per unit
volume of a material
• Density is calculated using this
formula
• Density = mass
volume
• Units are usually g/cm3