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Culture & Cycles - Science Lessons

“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
Lesson Title & Description
Objective
Students will:
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

1 class period

Explore
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
4 class periods
Explain/Apply
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

 

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.

 

4 class periods

Explain
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


2 class periods

Apply

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.

 

5-8 class periods

 

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

1 Day

Explore
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
1 Day
Explain
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

1 class period

Explore
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
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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PULSE is a project of the Community Outreach and Education Program of the Southwest Environmental Health Sciences Center and is funded by:


an
NIH/NCRR award #16260-01A1
The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award

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Supported by NIEHS grant # ES06694


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Last update: November 10, 2009
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