Articulation of the use of evidence and the model of energy flow in ecosystems in arguments from 12th-grade students

This study examines the use of the model of energy flow and its articulation with evidence at different epistemic levels by 12th grade students. The sample (N = 254) was obtained from an external standardized examination. The task requires students to justify the limitation on the number of levels in a trophic chain. The results show that: a) the students' use of the theoretical model is more sophisticated than their use of evidence; and b) from 12,2% of students that use evidence in three or four epistemic levels; the majority of them (11% from the total number) employ a complex model of energy flow. One implication is that although content knowledge is necessary in order to articulate evidence, it is not enough, and there is a need to carry out activities in order to promote the use of evidence in science classroom.