Answer the following questions based on your observations from
previous activity.
Name
Its Elemental
Gizmo Plant & Snail
1. What gas was produced by the snail?
2. What color change was triggered by the snail?
Complete the following before starting the Gizmo
3. What gas was produced by the Elodea plant in the light?

What important gas do we take in when we breathe in?
4. What color change did this trigger in the bromothymol blue?

Why don’t we run out of the important gases that we need to stay
5. What gas was released from a plant in the dark?
much?
alive?
How
Reset and clear the tubes. Continue experimenting to find
1. What numbers and combinations of organisms type yields the
most rapid increases in oxygen concentration?

What is a closed system?

Give an example of a closed system.
The effects of Bromothymol blue indicator
2. How long did it take for the full color change? ________ hours
3. What organism type yields the most rapid increases in carbon
dioxide concentration, how many were used and where were
they?
In this activity, you will create and monitor closed ecosystems with aquatic snails
and elodea plants. The bromothymol blue indicator in the test tubes will show carbon dioxide concentrations by changing color (yellow for high concentrations, blue
for low concentrations). Because plants convert carbon dioxide to oxygen, you can
infer that low carbon dioxide levels correspond to high oxygen levels
Circle the correct concentration in the chart below, using the information above
You must complete the above and get teacher stamp before continu4. How long did it take for the full color change? ________ hours
5. Suppose a closed test tube containing an Elodea sprig and a
snail were left in a lighted room for several days. Would the snail
and the plant survive? Yes
No
Why or why not?
color
carbon dioxide concentration
oxygen concentration
Yellow
HIGH
LOW
HIGH
LOW
Blue
HIGH
LOW
HIGH
LOW
ing to the Gizmo.
Get a computer, log on to the network.
Complete the Assessment Questions and note your score
Go to www.explorelearning.com and log onto Gizmos. If
you have forgotten your login or password please see me.
4
1
Understand the Gizmo set up.
In the Plants and Snails Gizmo™, each of the test tubes contains water and a small amount of bromothymol blue (BTB). BTB is a chemical indicator. An indicator changes color when the chemicals in the
water change
 With the lights set to on, drag a snail into one test tube and a
Light
Note down if the snail died in any of the trials
Tube
Contents
Initial color
of water
Prediction of
final color of
the water
O2 ____ CO2 ___
A
plant into another. Press Play
.
After 24 hours, what is the color of each tube?


snail
elodea
Select Show oxygen and CO2 values. Place the O2/CO2 probe in
each tube. The probe shows the levels of two gases, oxygen (O 2)
and carbon dioxide (CO2), in the tubes. We call these amounts
the gas levels.
O2 ____ CO2 ___
B
O2 ____ CO2 ___
C
 When the water turns blue, which gas is most common?
 When the water turns yellow, which gas is most common?
 What does it tell you when the water is green?
Click Reset
CO2 values.
Final color of the water
& gas concentrations
O2 ____ CO2 ___
D
Clear all of the test tubes. Turn on Show oxygen and
In the following activities you will be predicting what might happen in
the experiment before actually running the activity. It is very important
that you do preform the prediction step—predicting something that
didn’t happen is just fine, its data after all.
In the Gizmo you can click on snails and elodea sprigs and drag
them into test tubes, either in the Light room or the Dark room. Design a controlled experiment that has 3 experimental groups and one
control group. Both rooms must match each other.
Use the table provided to complete this activity. You must get your
set up and prediction completed and stamped before running the activity.
Set up and prediction for both Light and Dark have been
completed.
Tube
Contents
Initial color
of water
Prediction of
final color of
the water
Final color of the water
& gas concentrations
O2 ____ CO2 ___
A
O2 ____ CO2 ___
B
O2 ____ CO2 ___
C
O2 ____ CO2 ___
D
2
3