Are You Dense?
Deborah McMurtrie, Ph.D.
Bridget Coleman, Ph.D.
Gary Senn, Ph.D.
University of South Carolina Aiken
Handouts for this session can be found on the AMLE2015 app
Density
• DENSITY is a physical property of matter; how
tightly packed the molecules are
• The symbol most often used for density is ρ
(the lower case Greek letter rho).
• The formula to calculate density is ρ = m / V
ρ=m/V
Density = Mass divided by Volume
What does that mean, exactly?
What is Mass?
• Mass is the amount of matter in an object.
• Mass is how heavy something is (but without
gravity).
• We measure mass in grams (g) and kilograms
(kg).
What is Volume?
• Volume is how much space something takes up.
• Volume is the amount of 3-dimensional space
an object occupies.
• We measure volume in milliliters (mL), liters (L),
cubic centimeters (cc), or cubic meters (m3).
Displacement
To find the volume of an irregularly shaped
mineral (Garnet):
1.
2.
3.
4.
5.
Fill the beaker with water up to the 10mL line.
Carefully place the mineral in the water.
Where is the water line now?
Subtract 10mL from the new measurement.
That number is the volume of your mineral.
(Cubic centimeters)
Density of Minerals
• The minerals in your box all have the same
VOLUME but each has a different MASS.
• Feel each mineral sample. Estimate the order
from lightest to heaviest. Record your guess.
• Measure the MASS of each mineral and record
your results. Compare.
• You will have 15 MINUTES for this activity!
Estimate the Order
Bauxite
Galena
Quartz
Fluorite
Pyrite
Garnet
Feel each mineral sample. Estimate the order of the masses.
Measure the masses. Record on the lines.
B = Bauxite
=________ g
P = Pyrite
= ________g
F = Fluorite
=________ g
Q = Quartz
= ________g
G = Galena
=________ g
R = Garnet
= ________g
Write the masses in number order, from least to greatest.
Take 4 Measurements
• You will have 10 MINUTES for this activity.
• Six substances: Water, sand, salt, wood, iron
filings, and rubbing alcohol
• You will take 4 measurements of one
substance: 25mL, 50mL, 75mL, and 100mL.
Record your results for each on your data
sheet.
Density= Mass divided by Volume
Measure and record the mass for each substance. Graph the results. Calculate to find density.
SAND
Average Density = _________
SALT
Average Density = ___________
IRON FILINGS
Average Density = ___________
Volume
(mL)
25 mL
Volume
(mL)
25 mL
Volume
(mL)
25 mL
Mass (g)
Density
(g/mL)
Mass (g)
Density
(g/mL)
Mass (g)
Density
(g/mL)
50 mL
50 mL
50 mL
75 mL
75 mL
75 mL
100 mL
100 mL
100 mL
WATER
Average Density = ___________
WOOD
Average Density = ___________
RUBBING ALCOHOL
Average Density = ___________
Volume
(mL)
25 mL
Volume
(mL)
25 mL
Volume
(mL)
25 mL
Mass (g)
Density
(g/mL)
Mass (g)
Density
(g/mL)
50 mL
50 mL
50 mL
75 mL
75 mL
75 mL
100 mL
100 mL
100 mL
Mass (g)
Density
(g/mL)
Calculating Density
• Use your calculator to calculate the density of
your substance.
• Density = MASS divided by VOLUME (g/mL)
• Record your answers.
Graphing Density
• Your team will plot the data for ONE substance
on a transparency.
• X axis: Horizontal (bottom) shows VOLUME
• Y axis: Vertical (side) shows MASS
• Connect the 4 data points by drawing a
straight line.
• When you have finished, please bring your
transparency to the front.
Putting It All Together
• Density is the relationship between mass and
volume.
• Graphing the data points shows this
relationship.
• Water has a slope of 1.
• Substances with a slope >1 will sink.
• Substances with a slope <1 will float.
Related Middle Grades Standards
• Science: Density, Mass, Volume, Formulas,
Minerals, Measurement
• Technology: Calculators, Measurement Tools
• Engineering: Inquiry, Engineering Design Process
• Math:
Data Analysis, Graphing, Formulas,
Slope, Measurement
Session Evaluation
Let us know what you thought of this session. Complete an evaluation
electronically on the conference app, or complete the paper evaluation
located in the back of the program book.
CEU Code
Earn Continuing Education Units (CEU) to maintain your teaching
certification. Write down the CEU Code for every session you attend
on the CEU card located in the back of the program book.
CEU Code:
GP-54