Activity 7: Teaching Tips
Using Blackline Master Ecology 7.4: Transpiration Experiment Table, discuss
with the students the difference between the actual reading in the pipette and
the adjusted reading. Discuss the units of measurement to be used.
Using Blackline Master Ecology 7.5: Area of the Leaf Surfaces, point out to the students that they have to make approximations of those squares that are not
fully within the tracing. Discuss the units of measurement to be used.
Using Blackline Master Ecology 7.6: Rate of Transpiration, discuss that this
graph shows the amount of water lost per square centimeter over time.
Have the students figure out what they will put/plot on the x-axis and the y-axis. You can explain that the indicator of water loss is put/plotted on the y-axis.
The indicator is also known as the dependent variable. The time that elapsed independent variable is on the x-axis and the dependent variable is plotted on
the y-axis.
Ask what is happening in the photograph. Ask what the unit km3means.
Explain that this is a measurement of volume (V) that is a three-dimensional measurement involving length (l), width (w) and height (h) where V = l x w x h.
Using Blackline Master 7.1, discuss with the students the changes of state.
You may wish to provide the students with a copy of the diagram so that
they can label the changes themselves.
Blackline Master 7.3 is provided so that students can label some of the pathways
of the water cycle.
You may provide your students with a quiz to assess how well they understood
the water-cycle diagram. The following questions may be included:
1. Name the two cycles involved in the water cycle and differentiate one
from the other.
(The short cycle involves the oceans/seas, while the long cycle includes life processes and groundwater; the short cycle occurs faster, while the long cycle takes longer to complete; with the short cycle involving the large bodies of water, more evaporation occurs and it occurs faster resulting in more water vapor formation that eventually produces more precipitation after condensation, while in the long cycle, the life processes involved take longer to add water vapor to the atmosphere, thereby taking longer to form precipitation after condensation.)
2. Explain the life processes involved in the long cycle.
(Cellular respiration that occurs both in plants and animals releases water; transpiration that occurs in plants releases water through the leaves)
3. What are the similarities between the short cycle and the long cycle?
(Both involve the processes of evaporation, condensation and precipitation)
4. What is infiltration and how does it contribute to the water cycle?
(Infiltration occurs when water on the surface of the ground trickles down.
It contributes to the water cycle when it joins the groundwater that eventually ends up in the oceans/seas.)
Using Blackline Master 7.7: Major Biomes of the Earth, discuss with the students where the ice caps, glaciers, and permanent snow are located. In your discussion,
ask them how the global warming would affect the ice caps, glaciers, and
permanent snow. Ask them further what that would mean in terms of sea level.
(With global warming, glaciers, icecaps, and permanent snow would very slowly melt and would then make the sea level higher.)
Using Blackline Master 7.8: Human Population Growth, discuss the effect
of the growth of human population on the freshwater resource of the Earth. Emphasize that the freshwater resource remains constant while the human population does not.
Also discuss how pollution from the power plants affects the water cycle.
Sulfur dioxides (SO2) are produced when fossil fuels are oxidized. Nitrogen
oxides (NOx) are produced when atmospheric nitrogen is oxidized in car engines and furnaces. SO2 and NOx when combined with the atmosphere’s water vapor
will form sulfuric acid (H2SO4) and nitric acid (HNO3).
Setting up an ecocolumn is a very important modeling activity.
We strongly recommend that this Inquiring Further be done by the class.
A month before this activity, you can start telling the students to bring
2-liter soda bottles. This will give you enough time to collect as many
bottles as you can.
Discuss with the students that they have to figure out what would indicate
the effect of the acid rain. Will this be the death of the organisms? Will this
be the wilting of the plants? Tell them that these indicators are the dependent variables. Explain to them that the acid rain is what is causing the change that
is shown by the indicators. The acid rain is the independent variable.
The students can make “windows” on the side of the plastic bottle. They can
be holes through which acidity indicators like pH papers can be put through.
The caps on the bottles can also be pierced with holes to allow fluids to be introduced into the ecocolumn.
A possible source of sulfur oxide could be the smoke after blowing out
a burning matchstick. This could also be introduced into the ecocolumn
through the “window.” |