CTS Guide: Characteristics of Living Things, pp 98-99- Section IV Research Summaries
Concept of Living
By focusing on children’s understanding of the concept of death, Slaughter, Jaakkola, and Carey (1999) concluded that children’s concept of life transforms between the ages of 4 and 6 years from a focus on movement, activity, and usefulness, to life processes. At the same time, children’s concept of death changes from an early concept of death as living in an altered way, to death as an inevitable end to a life cycle and the final cessation of life. The authors claim that this cluster of concepts—life, death, and body functions that support life processes—constitutes the basic structure of an early biological theory of living.
Leach et al. (1992) and Driver et al. (1994): Studies found that many children, up to age 11, recognize animals as living but do not consider plants to be alive. Some children thought plants have a different life than animals. It can be difficult to convince children that even familiar living organisms, particularly plants, can demonstrate all of the characteristic processes of living things (movement, respiration, response, growth, reproduction, excretion and nutrition).
Stavy and Wax (1989): Children have difficulty accepting that seeds are living things, in some cases even though they also think that living things only develop from other living things
Carey (1985): Suggested that a progression of children’s concept of living is linked to their developing conceptual framework of biological processes (of which young children ages 4-7 have little knowledge). There is a marked increase in children’s understanding of biological processes by the ages of 9 or 10. As biological knowledge grows, animistic reasoning declines.
Piaget (1929:) Piaget carried out the classic early studies of children’s concept of living. He identified 5 stages: Stage 0: no concept of living; Stage 1: things that are active or making noise; Stage 2: things that move; Stage 3: Things that appear to move by themselves (including rivers and the sun); Stage 4: Adult concept (plants and animals). He also found young children attribute intention to physical phenomena of inanimate objects such as the sun is hot because it wants to keep us warm (animistic notions).
Criteria for Life
Skinner (2011): This study observed that teachers often define life using a set of characteristic processes of living organisms: movement, growth, nutrition, excretion, respiration, reproduction, response. and sometimes also control (maintaining a constant internal environment). Rote learning and mere recall of these criteria can lead to superficial learning without conceptual understanding. For example, recalling that respiration is a criterion is unhelpful for conceptual development without the understanding that this means that living organisms get energy from food. It is suggested that from the age of 11 these criteria based only on processes, can be supplemented with the idea that organisms are made of cells, as a further criterion (and in this case a structural one) for deciding what is or once was alive.
Some students use a people-association criterion to define life. They classify something as living because it is useful to or associated with people in some way. For example, in Venville’s study (2004), one child’s reason for classifying a table as living was “because people put dinner on it.” Some other children used a home criterion and said that if something was in a house or home it was living, and if it was outside a house or home it was not living.
Stavy (1987): Children aged 10-15 commonly used “breathing” as a criterion for life, but did not refer to “respiration”, while only 36% of children aged 14-15 used respiration as a criterion for life. Numerous studies have shown that children of all ages believe “breathing” and “respiration” to be the same thing, and that plants do not respire. One study found that children aged 13-14 were not aware of the link between nutrition and respiration, as they were unaware that food provides the material for cellular respiration
Bell and Barker (1982): In a sample of children aged 9-15 the majority were able to justify their things as alive or dead using terms chosen from the list of characteristic processes of living organisms, but many also incorrectly ascribed one or more of these characteristics (particularly movement) to inanimate objects such as rivers, fire, clouds and cars, and in doing so suggested that they are alive.
Elementary and middle school students use observable processes such as movement, breathing, reproducing, and dying when deciding if things are alive or not. High school and college students use these same readily observable characteristics to determine if something is alive. They rarely mention ideas such as “being made up of cells” or biochemical aspects such as “containing DNA.” Many educators agree that the emphasis in science education on the learning of facts has contributed little toward understanding. Students may be able to quote the seven characteristics of life but may not be able to apply them when determining if something is living (Brumby 1982).
Tamir, Gal-Choppin and Nussinovitz (1981): Research has suggested that the characteristic of life most commonly ascribed to animals was movement, while for plants it was growth, This may be because children do not readily associate movement with plants since it is more difficult to observe in plants.
Arnold and Simpson (1979): In a study of Scottish pupils ages 10-15, the four most popular criteria for identifying living things were eating/drinking, moving/walking, breathing and growing.