Academic journal article The American Biology Teacher

A Scoring Rubric for Students' Responses to Simple Evolution Questions: Darwinian Components

Academic journal article The American Biology Teacher

A Scoring Rubric for Students' Responses to Simple Evolution Questions: Darwinian Components

Article excerpt

The call to wit, It students Darwin's theory of evolution by natural selection has been made by a variety of professional organizations (e.g., American association for the Advancement of Science, 198,9; National Academy of Science, 1998; National Association of Biology Teachers, 1995; National Science Teachers Association, 1997). In addition to these national organizations, almost every state has science education guidelines calling for the teaching of evolution (Lerner, 2000; Moore, 2002).

Many administrators and policymakers believe that evolution is being taught, but teachers know that it is far more important that evolution be learned. Standards and curriculum documents frequently specify what is to be taught, but then provide little help with assessment and evaluation. This paper provides .t scoring rubric that will help teachers evaluate students' understandings of biological evolution.


In 1859 Charles Darwin published On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. Modifications to his initial theory were made in the mid-1900s in what is now called "the new synthesis" or "die modern synthesis," by scientists such as Theodosius Dobzhansky, Gaylord Simpson, and others. I here modifications included the fields of embryology, systematics, and genetics that were advancing rapidly since Darwin's time. Despite these and other modifications, the core of Darwin's theory remains unchanged to this day. The following outline of Darwin's theory will contain terms and concepts that were not known to Darwin, but cart easily be assimilated into his original theory; Darwin's original ideas remain the backbone of modern evolutionary theory.

Darwin's theory is complex in that many students, teachers, and even scientists frequently misunderstand and misuse it (Anderson, Fisher S: Norman, 2002; Bishop & Anderson, 1990; Rudolph & Stewart, 1998). However, its framework cart be divided into four straightforward components.

Darwinian Component #1: Variation

There exists within every population variation among individuals; the origin of that variation is chance.

Darwin did not know of DNA, gene expression, or mutations, but he did observe variation within species. Darwin viewed the origin of variation as being chance. (The idea of chance as a driving force in nature is at the core of Darwin's theory, and is also central to the conflict,' debate with creationists.) Why does one bird feed at a different time than another? Why is one fish a different color than another? Why is one cheetah faster than another? Darwin in saw it all as being related to chance. The term "random" and the concept of mutations are two related items that fit into this component of Darwin's theory. Students' responses are frequently full of buzzwords, such as mutation, that are associated with evolution. Simply slating "there was a initiation' does not represent much comprehension, but if associated ideas are also included, there then exists evidence that a student has a beginning understanding of evolutionary processes.

Darwinian Component #2: Genetics

Organisms pass information front one generation to the next.

A large section of this second component now relates to Medelian genetics, which post-dated Darwin, but he knew that something (i.e., information) was passed from generation to generation. Darwin developed his own theory of genetics that was based on blending inheritance-units called "gemmules," but that effort proved fruitless (Mayr, 1982). For students to rise this component, they must use phrases such as "the genes were passed to the next generation," or "information was passed to the next generation." Some students have difficulties with genetics concepts, which can be a significant barrier to a thorough understanding of evolution (e.g., Lawson & Thompsort, 1988).

Darwinian Component #3: Differential Survival & Reproduction

There occur in nature events in which some organisms die and others survive. …

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