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.