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Ecosystems | Goals

General Unit Information

The goal of the Ecosystems unit is to introduce students to organic matter and chemical energy (in the context of combustion) using the tools for reasoning and environmental literacy practices that students will engage with in other units. Students must be able to identify organic matter from inorganic matter, and understand how differences in the chemical make-up of materials influences how materials and energy are transformed and moved between systems.

Unit Goals

The tables below show goals for this unit in two forms. Table 1 shows unit learning objectives aligned with inquiry and application practices. Table 1 also contrasts the goal performance with performances of students at lower learning progression levels.
This table is followed by a list of Next Generation Science Standards (NGSS) addressed by this unit.

Ecosystems Unit

Type of Objective

Learning Objective

Challenges for Level 2 Students

Challenges for Level 3 Students

Application: Location Question

Locate organic and inorganic carbon pools in natural ecosystems (e.g., meadow) and human-managed ecosystems (e.g., farm):

·       CO2 in the atmosphere

·       Organic carbon pools: producers, herbivores, carnivores, soil carbon

Describe the “biomass pyramid” (producers > herbivores > carnivores) as a consistent pattern in terrestrial ecosystems

Describe pools as changing in size over time

Level 2 students will think of carbon a kind of material rather than as an atom in many carbon-containing molecules.

Level 3 students may not think of the same carbon atoms in the atmosphere, biomass, and soil

Application: Movement/Carbon Question

Describe carbon cycling within ecosystems as movement of carbon atoms among carbon pools associated with:

·    Movement of materials: Eating, defecation, death

·    Carbon-transforming processes: combustion, photosynthesis, digestion, biosynthesis, cellular respiration

Explain why the biomass pyramid is a consistent pattern in terrestrial ecosystems.

Explain changes in size of carbon pools in terms of fluxes into and out of carbon pools

Level 2 students will explain ecosystem processes as series of causally connected events (rabbits eat grass; foxes eat rabbits)

Level 3 students will recognize fluxes as involving movements of matter, but not that fluxes BOTH make one pool larger AND make another pool smaller.

Application: Energy question

Identify energy transformations involved in carbon fluxes

Describe energy as flowing through ecosystems, from sunlight to chemical energy to heat that is radiated into space

Level 2 students will describe energy as a cause of events rather than a conserved entity that can be traced through systems.

Level 3 students are likely to describe energy as recycling in ecosystems (e.g., through soil nutrients)

Citizenship decision-making

Explain the implications for resource use of humans eating meat or plant products: The same producers can support more humans as herbivores than as carnivores.

Level 2 students will think of diets as “good” or “bad,” but on the basis of health or general moral virtue, rather than reasoning about food chains.

Level 3 students may identify vegetarian diets as “better for the environment,” but their scientific rationale may be associated with more general notions of environmental harm.