E3.2C Describe the difference between oceanic and continental crust (including density, age, and
composition.
“I can explain the difference between continental and oceanic crust by their densities.”
Purpose: To investigate the density of oceanic crust and continental crust.
Hypothesis: To be written by students
If:
Then:
Because:
Materials:
Rock samples (Granite/continental crust, basalt/oceanic crust)
Triple beam balance scale
Data Table
500 ml Beaker
Procedures: Each table will receive two rock samples (granite, basalt), a triple beam balance, and a 500
ml beaker. After observing the rock samples, each student will write their own hypothesis about the
average density of the given rock samples.
Directions:
1. Calibrate the triple beam balance (zero)
2. Place the granite sample on the pan of the balance to measure its mass and record this
information on the data table.
3. Place the basalt rock on the pan of the balance and repeat step 2. Be sure to place the data in its
proper place.
4. Fill the 500 ml beaker approximately ½ full and record the volume of water in the data table.
This is the initial volume.
Convert all data regarding volume into cm3. Conversion: 1 ml = 1 cm3
5. Place the granite rock in the beaker. Record the volume of the water. This is the final volume.
6. Repeat step 5 for the basalt rock.
7. Find the volume of each rock sample by subtracting the initial volume from the final volume.
Use this formula for each rock sample: Final Volume – Initial Volume = Volume of Rock (cm3).
8. Find the density of each rock sample by dividing the mass of the rock by the volume of the rock.
Use this formula for each rock sample: Mass (g) ÷ Volume (cm3) = Density (g/cm3).
Record the density of each rock sample.
9. Refer back to your hypothesis for any possible revisions.
10. Write a conclusion of this process.
Rock Type
Mass (g)
Initial Volume
Final Volume
Volume of
Rock (F-I=)
Density
Granite
Basalt
Extension: If time permits, record the rock densities from each table for both granite and basalt. Take
the sum of each total and divide them by 7. This will give you a more precise density for each rock type.
Use your book or some other reliable resource to compare to your findings.
Rock
Granite
Basalt
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Final conclusion: (Remember to)



Restate your hypothesis
State if your hypothesis is supported, not supported, or inconclusive
Include data in explanation
Sum(Total) Average