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Culture
& Cycles -
Science Lessons
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“Where
does arsenic come from?” is answered in science class as
students explore geochemical cycles. Students explore not only
what the human health implications of arsenic in drinking water
are, but also why the scale of people affected by arsenic is so
wide, which has been found to be partly a result of the geochemical
cycles that shape our world. Plate tectonics, geochemical and geothermal
cycles, weathering and erosion, the structure of the earth, plus
rocks and minerals are the underling topics addressed in this unit.
Students’ work in this unit provides the necessary science
background students will need to complete the final project;
a persuasive public advisory to a community affected by arsenic
contamination.
Content standards addressed by this unit are within the Earth
and Space standards. Specifically, this unit deals with those
targeting geochemical cycles. |
Big Idea
|
Our
drinking water does not just appear at the faucet. Water
reservoirs that we use for drinking are part of a larger
geochemical system.
|
Essential
Question |
We
turn on a tap and get water, but where does it come from? |
Learning
Cycle
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Lesson
Title & Description
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Objective
Students will:
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Class
period & week
|
Engage
|
How
Much Water?
Students investigate the amount of
water available in different countries around the world
and compare it to their daily water use. |
Consider
their consumption of water and articulate questions about
their drinking water
|
|
Explore
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Beyond
the tap
Watersheds are complex, multifaceted
systems that serve a variety of needs for humans, plants,
animals, and invertebrates including providing fresh
clean drinking water and habitats. Humans can and do
have numerous effects on watersheds by changing water
flow patterns and introducing pollution. Through discussion
and creation of a model watershed, students will understand
how watersheds function.
|
Explore
their local sources for water, reviewing ground water and
watersheds using a variety of maps
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4
class periods
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Explain/Apply
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Groundwater
Modeling
In the previous lesson students explored watersheds as they
track where their water comes from. In this lesson students
further explore groundwater systems specifically and explain
how ground water moves through a watershed and how it can
become contaminated. Students build groundwater models and
then explain a mystery contamination determining point source
and non point source contamination. |
Evaluate
the effects on point and non-point sources of pollution on
water using a model. Build a model which represents an aspect
of the hydrosphere.
|
4 class periods
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Big
Idea
|
Elements
/chemicals/ compounds enter our water from different sources.
These substances can potentially affect our health. We
monitor our water to assess the quality of our water.
|
Essential Question |
How
do we know our water is safe to drink? How is water tested
for safety/purity? How do you know what is in your water? |
Learning
Cycle
|
Lesson
Title & Description
|
Objective
Students will:
|
Class
period & week |
Engage/Explore
|
A
Town in Trouble
Students explore water and wastewater treatment systems. Students
present the
information on various aspects of the contamination to a town
meeting. |
1. Identify
parameters and analytical techniques used to characterize
water contamination.
2.
Identify the consequences of high contamination
levels in the
water supply.
3.
Describe laws that govern the quality of the water.
4.
Differentiate
between drinking water and wastewater treatment systems & surface and ground
water supplies.
|
|
Explain
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Testing Your Water
Starting with a simulated water pollution case, students explore
a number of water quality tests |
Perform
a variety of water tests.
Define Acceptable Risk, EPA Standards and
Risk Benefits
|
|
Apply
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Bioassay
An inquiry lab using Daphnia as a bioassay organism.
Students develop questions and hypothesis and design an investigation
to
test their hypothesis.
|
1. Articulate
a research question and design and conduct an experiment
2.
Describe the dose response of Daphnia to a number of substances
Identify bioassays as a tool for toxicity.
|
|
Big Idea
|
There
are numerous considerations that each community must weigh
when trying to ensure water safety for its population.
Arsenic is a significant pollutant both locally and globally.
|
Essential
Question |
How
does Arsenic affect the community? |
Learning
Cycle
|
Lesson
Title & Description
|
Objective
Students will:
|
Class
period & week
|
Engage
|
Headline
Newspaper Article on new As standard implementation in AZ |
Identify
science questions about Arsenic and health
|
|
Explore
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Arsenic
and Old Lace
Chronic vs. Acute Poisoning (What’s in Your
Water)
Stations |
Explore
the broad health affects of Arsenic, using the questions
developed from the last lesson
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1
Day
|
Explain
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4
X 4
Students share with the rest of the class the health risks.
|
1.
Students will generate four statements and four questions
based on their current level of understanding of the article
from the engage lesson
2. Students will evaluate the statements and questions that they have generated
and those of their classmates and prioritize by narrowing 16+ to 2 representatives
to share with the class
3. Students will individually respond to each statement and question.
|
0.5
- 1 class period
|
Apply |
Arsenic
Globally
Class is split into 4 groups each studying one area of the world
affected by arsenic in the water |
Identify
how Arsenic got into the water (both natural and human-derived
reasons), what effect has it had on the people (breadth, depth,
scope, etc), what is being done about it, what are their recommendations.
|
2
Days |
Big Idea
|
Arsenic
exists in higher concentrations in some areas of the bedrock
than in others and consequently may also exist in the drinking
water in higher concentrations. Arsenic, like other elements
such as (what other elements)? becomes concentrated in
the bedrock as a result of hydrothermal systems.
|
Essential
Question |
How
does Arsenic get into the drinking water? |
Learning
Cycle
|
Lesson
Title & Description
|
Objective
Students will:
|
Class
period & week
|
Engage
|
Finding
the Mother Load
Students are prompted to ask why some minerals are found in great
concentrations than others. |
Establish
where a lode deposit is located using a topographic map,
stream sediment data and deductive reasoning
|
|
Explore
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Why here?
Students examine the basis of hydrothermal systems using a
Flash animation |
Articulate
one process by which minerals become concentrated in the
bedrock
|
2 class periods
|
Explain
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What
happens to Create the Lode?
Students use a laboratory exercise, precipitation rates and other
possible solutions to explain how hydrothermal systems result
in the concentration of some minerals. |
Explain
how hydrothermal systems result in the concentration of some
minerals
|
3-4 class
periods
|
Apply |
Its not
Just Gold
Students apply their understanding of hydrothermal systems that
lead to lodes of gold to explain the location of arsenic. |
Explain
the relationship between arsenic and gold deposits using their
background in hydrothermal systems |
1-2 class
periods |
The Major Project
At the end students will be able to explain to their community
what arsenic is, why it is a problem, why it gets in the water,
what the water utility and the EPA does. They will also be able
to do this for another pollutant of interest to them in their
community and then bring to class their findings and discuss
acceptable risks to their community.
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