Clarification Statement - S.MS.LS.2.3.CS:
Emphasis is on describing the conservation of matter and flow of energy into and out of various ecosystems, and on defining the boundaries of the system.

Assessment Boundary - S.MS.LS.2.3.AB:
Assessment does not include the use of chemical reactions to describe the processes.

Science and Engineering Practices - 6-8.SEP2.3:
Develop and use a model to describe phenomena.

Disciplinary Core Ideas - S.MS.LS.2.3.DCI:
LS2.B: Cycle of Matter and Energy Transfer in Ecosystems •Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem.

Crosscutting Concepts - CC5.7:
The transfer of energy can be tracked as energy flows through a designed or natural system.