MI BIG
Ecosystems III.5
Map (html) | Map
(Inspiration)
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All students will explain how parts of an ecosystem are related and how
they interact.
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All students will explain how energy is distributed to living things in
an ecosystem.
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All students will investigate and explain how communities of living
things change over a period of time.
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All students will describe how materials cycle through an ecosystem and
get reused in the environment.
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All students will analyze how humans and the environment interact.
Overview
Don't it always seem to go,
That you don't know what you've got till it's gone.
They paved paradise
And put up a parking lot.
Big Yellow Taxi--Joni Mitchell
Ecology may be the most interesting topic for children and teachers in our
school curriculum. People of all ages seem to have an innate curiosity
about the world in which we live and the animals and plants with which we
live. We are also becoming increasingly aware of the effects our actions
have on the world around us. In the study of ecosystems, students consider
the fascinating, challenging and exciting interactions among species and
between species and environment over time.
Essential Background Narratives
Explain how parts of an ecosystem are related and how they interact.
Explain how energy is distributed to living things in an ecosystem.
Investigate and explain how communities of living things change over a
period of time.
Describe how materials cycle through an ecosystem and get reused in the
environment.
Analyze how humans and the environment interact.
It is important for students to learn about many ecosystems, but they need
to begin with those that have the closest connection to them. Very young
children think in terms of organisms that are around them such as pets,
animals in zoos, and houseplants. At a young age, many children think
humans help to feed wild animals. As they mature, children begin to
understand the concept of populations of organisms in the wild. The
concept of populations is most clearly understood in terms of food chains
and food webs.
In elementary school, students should be introduced to food chains and
learn about some of the organisms involved. Early in this time, students
may only be able to understand the relationship between two organisms.
Later, students should be able to identify the organisms involved in both
food chains and food webs and the feeding relationships that occur.
Interestingly, children in elementary school may not believe that food can
be a scarce resource in a food web. They think that all animals are more
like people in that animals can change what they need to eat whenever they
want according to what is available. Students in these grades should be
able to describe all of the basic requirements needed for all living
things to exist.
As students progress through the upper elementary grades and go into
middle school they should become more aware of different interactions
between organisms, besides food. For example, there are mutually
beneficial relationships like plants depending on animals for pollination.
There are also competitive relationships in which different animals with
similar environmental requirements compete for the same resources. In the
middle school, students should be made aware of the relationships between
organisms in which neither could survive without the other. By high
school, students should be able to describe common ecological
relationships between and among species and their environments. They
should understand the difficult concepts of competition, territory, and
carrying capacity among others.
Students misunderstand the concept of energy. Young children think about
food as something that they eat. They do not think about food being
converted into a useable form of energy. As middle school students, they
start to understand the idea of converting energy, but not into anything
in particular. It is just converted. They also have trouble understanding
the role of plants and the process of photosynthesis. Students often think
that anything taken in by plants is food. Even when they start to
understand photosynthesis, most students still believe that plants still
take in some kind of food for themselves. Soon they start believing that
the food the plant makes is for animals, including humans, not the plant
itself.
Students should be able to describe how organisms acquire energy directly
and indirectly from sunlight. They should also be able to explain how
energy flows through ecosystems. The arrows that we use in food chains and
food webs to model energy flow are also confusing for students. Even when
it appears that students understand food webs and food pyramids,
additional questioning shows that students do not understand the crucial
role of solar energy and photosynthesis. Even at the high school level,
students believe that higher order consumers can survive without plants if
there is enough prey and they keep reproducing. The misunderstanding
becomes even greater when students study aquatic environments because they
do not understand what a plant really is and because their experiences
with aquatic environments are very limited.
Students in elementary school generally have experiences growing
particular plants and animals. They also have opportunities to see
examples of other ecosystems both managed (farms and gardens) and
unmanaged. As students move to middle school they are more prepared to see
the effects that changes in one population may have on another. This
interdependence is also discussed in the previous benchmark. Students
should be able to describe the predictable succession of an ecosystem over
time. They should describe the general factors that regulate population
size in ecosystems. Students should describe how an ecosystem responds to
events that cause it to change. It is important to note that ecosystems
can change dramatically and have rapid fluctuations. Over the course of
time, the system is fairly stable.
Carbon and soil nutrient cycling are critical to understanding how
communities change over time. High school students need support in
understanding that when organisms die they do not simply "rot
away" but that the matter is converted into other materials in the
environment. Students need to be reminded that microorganisms are
responsible for the decay. High school students frequently think about
matter as being created or destroyed rather than it cycles through the
ecosystem to be reused in a different form.
Students need to learn the role that animals play in design of systems
managed by humans. Students should describe the positive and negative
effects that humans have on the environment. They should understand the
systems that best encourage the growth of plants and animals and then can
be managed by humans. Finally, they should describe more positive and
negative effects that humans have on the environment. Students in middle
school should be able to explain how humans benefit from the use of plant
and animal materials. In middle school, students should be able to
describe ways in which humans change the environment. In high school, they
should be able to explain the effects that agriculture and urban
development have on ecosystems.
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