Academic journal article Science Scope

Creative Natural Selection

Academic journal article Science Scope

Creative Natural Selection

Article excerpt

In our science classrooms, students respond favorably and with more enthusiasm when we engage them with doing activities and building their own connections, as opposed to simply listening to or reading about the important concepts. Creative activities are important in science classrooms (Taylor et al. 2008) because creativity is not only an integral component for knowledge construction (Csikszentmihalyi 1996) but also can make instruction more effective (Niaz 1993). Our own experience demonstrated that creative class-room investigations inspire students and promote effective learning environments (Clary and Wandersee 2011a).

In an attempt to integrate a geological component in a classroom investigation of biological evolution, we developed two activities with an interdisciplinary approach that includes the role of the environment. Our activities not only offer alternatives for addressing the mechanism of natural selection, but they also have been affirmed by our students as their classroom favorites. We like to think that they evolved through our students' natural selection processes.

Activity 1: Predict a pollinator

The classroom investigations we previously used for instruction in natural selection provided a series of modifications of an organism (such as bird beaks) and required middle school students to fit the appropriate beak modification to a specific food source. We modified the activity by providing an environment that required students to creatively predict a potential solution that would fit within that environment.

According to Darwin's theory of evolution, a population of organisms can change, or evolve, over time via the mechanism of natural selection. Variations exist within any population, but not all variations are best suited to the environment. Organisms also produce more offspring than survive. Therefore, the offspring with the variations that are better suited to the environment are more likely to survive and reproduce. A population typically will exhibit those characteristics that have been "selected" by the environment because they better ensure the success of the organism. We ask students to use this mechanism to predict which traits of an organism could have been naturally selected by an environment over time.

Pollinators include organisms such as insects, birds, bats, and other vertebrates that transfer pollen from flowers' anthers to the stigma, eventually resulting in fertile seeds. Pollinators may have specialized beaks or proboscises or even pollencarrying structures (such as the hind legs of honeybees) that allow them to efficiently feed on and collect the nectar or pollen of the plant. The transfer of pollen that leads to fertilization is usually an unintended result of the feeding process. Pollinators do not develop in isolation, and their natural selection can be in response to the biological drive of the plants. (The BBC film Sexual Encounters of the Floral Kind, which can be partially viewed or purchased on-line, may provide a good introduction to this topic.)

We ask our students to use the Darwinian model to create a pollinating bird of an imaginary flower on an unusual cactus (see Activity Worksheet 1).The pollinator must effectively consider the size of the fictional cactus we provide, its dangerous spines, and the depth of the pollen within the trumpet flower. Additional considerations are that the bird is secretive and has been viewed only fleetingly at night. Teachers may require either a two-dimensional drawing (computer generated or free-hand sketch) or a three-dimensional model of the potential pollinating bird. In the past, we provided the classroom art bin, a large plastic storage box filled with assorted construction paper, cardboard, foam pieces, pom-poms, and yarn for materials, or alternatively assigned this as a homework project in which students used materials from home. The Predict a Pollinator activity can also be modified to require only recycled materials for the model's construction, including reappropriated cardboard, packing materials, and plastic containers. …

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