This section is a set of tasks related to Energy Transformations. The typical order of activities for the Ecosphere Module is to Complete Matter Transformation Parts A, B, C & D. Then complete Energy Transformation Parts A, B & C (this page). Then return to the Matter Transformation problems and do Part E on Cellular Respiration. If you skip a particular part of the module, studies have shown that students do not develop the scientific understanding that that part addresses.
The Energy problems are designed to further students’ development of an interconnected way of thinking by refining their understanding of the distinction between matter and energy. Interviews with students during the development of these tasks revealed multiple and sometimes incompatible schemes of matter and energy that varied depending on the context (Maskiewicz, 2006). If students are to consider matter cycling and energy flowing as micro-level processes essential to the functioning of a biological system, then they needed to reorganize their schemes about matter and energy to include an understanding that (a) in a biological system matter and energy are not the same, they are distinct; (b) matter cycles and energy flows through a biological system; and (c) energy degrades in a biological system, and therefore there must be a constant input of energy. Helping students develop these ways of understanding was the goal of the Energy Problems (see Table 6). These problems are designed to instigate students to access prior knowledge learned in middle and high school—energy degradation.
Students should be given several minutes to work independently on Part A. Then they can discuss their ideas and create an energy diagram as a group. Based on previous implementations of these problems, students represent energy traveling from the sun to the algae, and then cycling through all the organisms back to the algae, much like their matter diagrams from the Matter Problem. This diagram of energy cycling serves the purpose of providing a context for perturbation. The intent of Part B is to bring to the students’ attention two incompatible schemes that they hold: If energy cycles as matter does, the plant would be able to survive for a long period of time in the dark. However, the students also know that a plant will die after days or weeks in the dark. Once the students are sufficiently puzzled, the problem creates in them a need to draw upon a different scheme that they already hold: in food web relationships there is a loss of energy between trophic levels. So Part B of the Energy Problem creates cognitive puzzlement because the problem brings to the students’ attention inconsistencies or incompatibilities in their existing schemes. To resolve these incompatibilities the students need to reorganize their schemes of matter and energy.
In previous implementations of this problem situation, students develop solutions to Part B rather quickly; 15 to 30 minutes. Students from the high school level through undergraduate do indeed bring to the situation their knowledge about the loss of energy in trophic relationships, and they know that the energy is lost in the form of heat. Sometimes this happens as quickly as five minutes into developing a solution. Although they have previously developed schemes to account for the energy relationships in a biological system, they have not made the connection between their understanding of the loss of energy between trophic levels and the need for a constant input of energy to keep a system functioning. It is likely that they had never previously experienced the need to distinguish between matter and energy. Since they know that a plant would die in the dark—but also know matter cycled in the sphere—distinguishing matter from energy becomes necessary.
Part C provides an opportunity for the student to apply their understanding of energy degradation to the tracing of energy in a system. The students often struggle with the idea that the producer loses energy or that 100% of the energy is eventually transformed into thermal energy. This problem provides the opportunity for a generative whole class discussion about the flow of energy through a biological system and the need for a constant input of energy.