Table 3.

Sample student responses and codes to the “Grandma Johnson” question

Example student response	Score	Notes
Her body would have its energy absorbed into the ground and then that energy is moved from the ground into the coyote's leg because of recycled energy and recycled matter.	N	This vague and nonsensical answer confuses energy with matter.
Grandma Johnson decomposed into various nutrients which entered into the soil of the ecosystem. These nutrients were used by plants to grow. These plants were then eaten by a consumer, such as a rabbit. That rabbit was then consumed by the coyote.	XCD	This student thinks that decomposed matter enters plants through their soil.
The decomposer would eat her carbs and then the decomposer would gain carbs. Through cellular respiration by the decomposer carbon would be released into the environment. The coyote would then eat a decomposer which has carbs and now the coyote has it's own carbs.	ADY	This student knows that a decomposer can perform cell respiration, however, misses the role of plants.
Her matter is used by the plant (CO2 for example), which is eaten by the herbivores, which is eaten by the coyote. This matter is used to perform certain tasks, and in this case performing a muscle leg of a coyote.	BCD	This incomplete answer fails to account for how carbon dioxide was generated. Because a decomposer was not mentioned, that pathway (A) was not coded.
Grandma Johnson (now a dead organism) would store the carbon atom as a carbohydrate; when she is eaten by bacteria (a decomposer) the carbon atom will transfer to the bacteria as a carbohydrate. After cellular respiration the carbon atom will be released into the atmosphere as a CO2 molecule. This CO2 molecule will be used by a plant during photosynthesis and will be stored as a starch within the plant. The plant will then be eaten by a mouse who will store the carbon atom in the form as [sic] glycogen. When the mouse is eaten by a coyote the carbon atom will be transferred to a muscle cell in the coyote's leg.	ABCD	This example of correct understanding illustrates a complete and accurate account of the carbon cycling in this scenario.