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Arsenic
and Old Lace
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| Time: |
1.5 class
periods |
| Prep Time: |
15 minutes – photocopying
Article |
| Materials: |
See
Resources |
Abstract
In this explore lesson, students learn
about the origins, issues and problems associated with
arsenic through history. The end goal of this learning
cycle is to become more acquainted with the effects
of arsenic poisoning, different ways that arsenic can
get into someone’s system, and to make intuitive
assessments of what the terms chronic and acute mean.
They should also be able to discuss their own ideas
about how the risk levels set by health agencies are
determined.
Objectives
Students will:
1. Read about specific instances of arsenic in
history and share these stories with each other.
2. Identify, after reading the articles and sharing,
what role arsenic played, how arsenic enters the system
and what its effects are.
3. Make assessments of what chronic and acute mean
and assign each term to each story they have read.
4. As a class, discuss what counts as an acceptable
risk of arsenic exposure in each case and identify
what factors should be taken into account.
National
Science Education Standards
CONTENT STANDARD F: Science in Personal and
Social Perspectives
ENVIRONMENTAL QUALITY
- Natural
ecosystems provide an array of basic processes that
affect humans. Those processes include maintenance
of the quality of the atmosphere, generation
of soils, control of the hydrologic cycle, disposal
of wastes,
and recycling of nutrients. Humans are changing
many of these basic processes, and the changes may
be
detrimental to not only to the human
populations, but also to the
environment.
- Many
factors influence environmental quality. Factors
that students might
investigate include
population growth, resource use, population distribution,
overconsumption, the capacity of technology to solve problems,
poverty, the role of economic, political,
and
religious views, and different ways humans view the earth.
NATURAL AND HUMAN-INDUCED HAZARDS
ß Some hazards, such as earthquakes, volcanic eruptions,
and severe weather, are rapid
and spectacular. But there are slow and progressive changes that also
result in problems for individuals and societies. For
example, changes in stream channel positions,
erosion of bridge foundations, sedimentation in lakes and harbors,
coastal erosions, and the continuing erosion and wasting
of soil and landscapes can all negatively affect
society.
Teacher
Background
Teachers should have read the articles and be aware
of the effects of arsenic poisoning.
Arsenic through history:
There are a number of different sources of arsenic “contamination” of
the environment- geological processes (aided or not
aided by humans), mine tailings, and pesticide deposition.
Mine tailings and pesticides are an important part
of the whole picture, but the more interesting and
challenging problem of environmental levels of arsenic
is from the first category, geological processes.
Arsenic finds its way into our drinking water and
our bodies from different geological processes to
different chemical reactions that take place, modulating
that level of available arsenic and its effects.
It is important for students to take away this picture-
of a complex network of environmental influences,
the ‘abiotic ecology’ of arsenic , as
well as how the picture continues to come into focus.
They will do this by learning how we get a picture
of what is going on through the effects on people
(this learning cycle) as well as how the levels are
set and the regulations are enacted through remediation
and legal consequences.
General background: http://www.dchtrust.org/arsenic_king_of_poison.htm
Related
and Resource Websites
Killer wallpaper: http://www.popularscience.co.uk/features/feat17.htm
Madness of King George (antimony, arsenic and porphyria):
http://news.bbc.co.uk/1/hi/health/3889903.stm
The many faces of arsenic: http://news.bbc.co.uk/1/hi/health/medical_notes/459078.stm
US rice: http://www.nature.com/news/2005/050801/full/050801-5.html
Medical- current: http://phys4.harvard.edu/~wilson/arsenic/Image_Makeover1.htm
General: http://www.dartmouth.edu/~toxmetal/TXSHas.htm
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Activity
1. As students walk in, you should have the following
question on the board: “Have you heard of arsenic
poisoning?’ What does this phrase make you think
of?” Give them 5 minutes to write down their answers.
2. Call on students to read their answers and categorize
them on the board. This allows you to get an idea what
the students’ prior knowledge is. You may have
to prompt them or ask leading questions to get them to
think a bit more broadly, as the previous lesson will
have alerted them to arsenic as a contaminant in the
water supply.
3. Once you have given the class a glimpse of what their
classmates have thought of, pass out one article per
student for a 15-25 minute reading time. Have the students
highlight one sentence that strikes them as the most
important in their article.
4. Gather students who have read the same article into
groups. Within groups, students will share their sentences,
and then will come up with a summary of the article as
a group.
5. Partway through their discussion, put the following
labels on the board: Textiles, medicines, geology, pesticides,
mining, other. Tell students that, along with their summary,
they must identify the term that matches the role of
arsenic in their article.
6. Within each group, students will be numbered 1-4 (or
5 if there are more students) and then through a jigsaw
be placed in groups where each article is represented.
They will then share their article’s summary and
term with the group.
7. When the groups complete their discussion, each article’s
title and term will be read for the class.
8. The teacher should post each article along with the
term chosen by the group on the wall.
Chronic vs. acute (day 2)
9. Ask students to define the word “chronic” on
a sheet of paper.
10. Ask students to define the word “acute” on
a sheet of paper.
11. Collect the papers
12. Give the terms and their definitions on the board.
13. Have the students, as a class, decide which term
fits each arsenic article.
14. Ask the students to identify factors that are important
in assigning each article (dosage, time exposed, how
people were exposed, effects of the poisoning, chemical
state of the arsenic, etc.)
15. Ask students to give ideas about how much arsenic
is an acceptable risk in each case. Does this differ
from case to case? Why or why not?.
Homework
Have students answer one of the following questions in
a one page essay:
A) How has the view of arsenic changed over time, and
what do you expect in the future?
B) How would you educate someone on the risks of arsenic?
C) What more do you need to know to make educated decisions
about arsenic levels in your water supply?
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Embedded
Assessment
This
lesson allows a teacher to assess student preconceptions
about arsenic, and the definitions of ‘chronic’ and ‘acute’.
It gives the students a wide ranging view of arsenic
though history and to synthesize this information in
ways to help them make decisions about acceptable risk
and regulation of arsenic exposure to humans. By attacking
the arsenic problem at an historical level, students
see how our knowledge of arsenic has changed over time.
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