Name: ______________________________ Teacher: _________________ Date: __________
Activity 1.2: Assessing the Expressing Ideas Tool for
Ecosystems
This Expressing Ideas Tool should be part of a brainstorming and elicitation session: the
goal is to get students to express a wide range of ideas, even if they are incorrect.
Ideally, students will come to recognize that they have many different ideas about what
happens when ethanol burns, as well as unanswered questions.
Level 4 responses are in bold blue italics below. Remember Level 4 is the eventual
learning goal; we do NOT expect most, possibly any, students to produce these
responses at this point in the unit. This activity has “assessing” in the title because we
do NOT recommend giving your students a grade based on the scientific accuracy of
their responses at this point in the unit. It is designed to be used as a tool for formative
assessment.
The diagram shows a meadow
ecosystem that includes rabbits,
foxes, and grass.
1. The diagram shows that there is more grass than rabbits and more rabbits than
foxes. Does it have to be that way? Explain your reasoning.
Level 4 responses may indicate that as the grass gets consumed by the
rabbits, most of that mass is lost through cellular respiration of the rabbits. So
by the time the rabbits get consumed by the foxes, most of the grass would
have already been consumed by the rabbits. Level 4 students may also add
that 90% of the total mass gets lost at each consumption, but this is more
sophisticated of a response than we would expect from a middle or high
school student.
Level 3 responses may suggest that so much grass is needed because animals die
or use the food for energy, or that the food they eat is turned into energy and
“burned up” (note: it is common for level 3 students to suggest that matter can be
turned into energy).
Ecosystems, Activity 1.2
Carbon: Transformations in Matter and Energy
Environmental Literacy Project
Michigan State University
Name: ______________________________ Teacher: _________________ Date: __________
Level 2 responses might focus on describing a food chain (e.g., carnivores eat
herbivores while herbivores eat plants) without explaining why so much grass is
needed to support a few foxes other than to say that there has to be more grass
(plants) to support the rabbits (herbivores) and that there are fewer foxes
(carnivores) because foxes are at the top of the food chain.
2. Suppose a lot of new foxes move into this ecosystem. What do you think will happen
to the populations of the grass, rabbits, and foxes over time? Explain your
reasoning.
A Level 4 response may indicate that the number of rabbits will be higher than
the number of foxes because as organic materials are eaten in a food chain,
most of the food is used for cellular respiration (to release energy for the
organism). One fox will always need several rabbits (lots of organic carbon
and chemical energy) in order to stay alive, and most of the organic carbon
that makes up the bodies of the rabbits will be respired by the fox. Student
responses may also indicate that the grass will initially decrease when the
rabbit population increases, but then should stabilize back to its initial
condition over time.
Level 3 responses might suggest that because foxes are at the top of the food chain,
they need a larger rabbit population to maintain their own population. However,
students may not be able to explain that this is a result of mass from the rabbit
bodies being released into the air as CO2 during the fox’s cellular respiration. They
might also suggest that all animal populations fluctuate because when the foxes eat
too many rabbits, there will be less rabbits than foxes, but then as the rabbit
populations increase, there will be more rabbits again.
Level 2 responses might suggest that there will be more foxes than rabbits because
foxes are at the top of the food chain/trophic level and have no predators; that the
populations will be about equal because they don’t change; or that there will be less
rabbits because the foxes eat the rabbits; or that the rabbits will thrive because there
are lots of grass in the ecosystem.
Ecosystems, Activity 1.2
Carbon: Transformations in Matter and Energy
Environmental Literacy Project
Michigan State University