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Earth Science Regents Performance Test Bead Drop:“Settling it once and for all!”
Bead Drop Research Team -SUNY Oneonta Dr. Jim Ebert, Earth Sciences Dept. Ron Chapin Trish Emmons Don Zaengle Gerald Jones Tom Sansone
Student Participants Student participants in the Station
5 research project were Secondary Education/Earth Science Students enrolled in ESCI 315: Laboratory Techniques in Earth Science in the Spring semesters of 1999 and 2000
Variables investigated in 1999 Variation in bead density with
temperature Variation in fluid density with
temperature Changing time to terminal velocity
with fluid height in column Variation in fluid viscosity with
temperature
Research in 2000 Focus on viscosity change with
temperature Construct correction curves? Examine other fluids with less
temperature-dependent viscosity
Let’s drop some Beads!!
ESCI 315 data for Red Beads
4 mm Beads Temperature vs Settling Time
05
1015202530
Temperature (C)
Se
ttli
ng
Tim
e (
sec)
Veg Oil (n=92)
All (n=91)
ESCI 315 data - Green Beads
6 mm Beads Temperature vs Settling Time
0
5
10
15
Temperature (C)
Se
ttlin
g T
ime
(s
ec) Veg Oil (n=99)
All (n=84)
ESCI 315 data – Orange Beads
8mm Beads Temperature vs Settling Time
0
2
4
6
8
10
21 22 23 24 25 26 27 28 30 32
Temperature (C)
Se
ttlin
g T
ime
(s
ec) Veg Oil (n=91)
All (n=89)
Settling Time –expanded scale
8mm Beads - Veg. Oil Solution Temperature vs Settling Time
2
3
4
21 22 23 24 25 26 27 28 30 32
Temperature (C)
Se
ttlin
g T
ime
(se
c)
n=91
Settling Time –expanded scale
4mm Beads - Veg. Oil SolutionTemperature vs Settling Time
6
7
8
9
10
21 22 23 24 25 26 27 28 30 32
Temperture (C)
Se
ttli
ng
Tim
e (
se
c)
n=92
Range of settling timeswith temperature
4 mm Beads Temperature vs Settling Time
Raw Data
05
1015202530
Temperature (C)
Tim
e (
se
c) Veg Oil (n=92)
All (n=91)
Viscosity and settling time Water-based solutions show significant
changes in viscosity with changes in temperature
Settling time may vary by up to 50% over range of typical classroom temperatures
Vegetable oil shows very slight changes in viscosity and therefore settling time with changes in temperature
“Channeling”and water-based solutions Water-based solutions displayed an
unexpected “channeling” effect A visible “channel” was observed in the
fluid column Beads entering this channel settled
significantly faster than beads outside the channel
Settling times in water-based solutions may vary by up to 6 seconds at a single temperature!
CONCLUSIONS Use Vegetable Oil for Station 5 Viscosity and therefore settling time
is less affected by temperature during administration of the practical
With vegetable oil, it should be possible to make up a single key for each set-up and not have different keys for different times of day/temperatures.
Helpful hints for Station 5 USE VEGETABLE OIL instead of water-
based solutions. Oil is less susceptible to temperature-induced changes in viscosity. Therefore there will be less “drift” in settling time. Also, “channeling” is not a problem.
Be aware that settling times in oil are faster than water-based solutions. Adjust timing marks on columns to give appropriate settling times.
Helpful hints for Station 5 Use Number 7 or 8 rubber stoppers
in the bottoms of columns. They give a better seal than the plastic fittings.
Place the bottom of the tube in a plastic beaker or whipped topping container to ease clean-up in the case of minor leaks.
Helpful hints for Station 5 Place a film-cannister
“bailer” at the bottom of the tube to retrieve beads. Holes in the cannister allow fluid to drain out.
Bent pieces of coat hanger are good for the “hook” and straightened coat hangers work well to retrieve the bailer.
Thanks to Irv Soden for this suggestion.
Helpful Hints for Station 5 Plastic petri (culture) dishes work
well for holding the beads at each station.
Use masking tape to anchor the dishes to the table top to minimize the chances of students spilling beads (of course, this NEVER happens!)
Helpful Hints for Station 5 Glue beads onto the station directions so
that there is no ambiguity over which beads the students should use for each trial.
Use plastic page protectors for the station instructions. This prevents students from writing on them, shields them from spills and preserves them for future use.
CLEAN UP Hot soapy water works well for
removing oil from beads, tubes and stoppers. You can even use the detergent from previous years!
Oil can be kept in the original bottles indefinitely.