CTS Guide: Decomposition and Decay pp 112-113- Section IV Research Summaries
Decay
Driver et al. (1994): Several research studies have identified children’s common notions about decay. In response to research questions related to the “disappearance” of dead animals or fruits on the surface of the soil, young children thought dead things just disappear and did not allow for ideas about conservation of matter after death. Most of these children thought of decomposition as the total or partial disappearance of matter. Generally, students are unaware of the role that microorganisms play in ecosystems, especially microorganisms’ role as agents of change, such as decomposers and recyclers.
Hogan (1994): When fifth and sixth graders were asked what makes a dead thing disappear, some of their comments included, “When it’s been dead a long time and gets real old, it breaks up and disappears,” “When the rain and wind come, the dead plant spreads out into the dirt,” “When we die they put us in a coffin and bury us, and while we’re in the coffin we dissolve” Some students were found to say things “decay” or “rot away” without realizing that microorganisms cause the decay process as they use dead material for food.
AAAS (2009): Some middle school students think dead organisms simply rot away. They do not realize that matter from dead organisms is converted into other materials in the environment. They may recognize recycling of material through soil minerals but fail to incorporate water, oxygen, and carbon dioxide into matter cycles. Even after specially designed instruction, students would cling to the misinterpretation that materials are recycled primarily through soil in the form of minerals.
Decomposers and Role of Microbes
Students in the elementary grades may initially be aware of decay as a process without knowing about decomposers as organisms that break down dead plants and animals for food. Even when they learn about microscopic bacteria and fungi as decomposers, they are likely to view them as enablers of decay rather than consumers of dead plants and animals (Jin and Anderson 2012).
Some middle school students see decay as a gradual, inevitable consequence of time without need of decomposing agents (AAAS 2009).
A study by Hogan and Fisherkeller (1996) of sixth grade students showed that some students understood that decomposers break down dead plants and animals and were able to explain the process in terms of decomposers’ need to consume food. Some of these students could also explain how refrigeration and chemicals prevent food spoilage by microbes. However, most of the students also discussed decomposition as also being a physical process, similar to weathering.
In a study of 15- to 16-year-olds, 65% used words like bacteria, fungi, and decomposers, but were not sure about their roles. Although older students tend to offer more factors to explain decay, there was little evidence that they had an understanding of how physical factors relate to the action of microbes. Younger students tend to think that insects break up material once it has started to rot of its own accord. In response to research questions related to the “disappearance” of fruits on the surface of the soil, young children thought dead things just disappear. Generally, students are unaware of the role that microorganisms play in ecosystems—especially their role as agents of change, such as decomposers and recyclers (Driver et al. 1994).
Some students say things “decay” or “rot away” without realizing that microorganisms cause the decay process as they use dead material for food (Hogan 1994).
Some studies have shown that children up to middle school associate microorganisms only with disease and decay is associated with rotting food, without linking it to microorganisms (Leach et al. 1992).
In a study of Israeli students ages 13-16, one third said if it were possible, they would eliminate all microorganisms from Earth (Barenholz and Tamir 1987).
Conservation of Matter During Decomposition
Leach (1992): A study revealed that 70% of 11- to 13-year-olds lacked an understanding of conservation of matter to explain what happens after organisms die, even after the topic is taught. Furthermore, they found that up to age 16, few students had a view of matter that involved conservation in a variety of contexts, including decay.