Academic journal article The Science Teacher

A Cool Controversy: Exploring the Nature of Science Using a Historical Debate about Glaciers

Academic journal article The Science Teacher

A Cool Controversy: Exploring the Nature of Science Using a Historical Debate about Glaciers

Article excerpt

As society becomes more technological, the need for scientific literacy grows (Schweingruber, Duschl, and Shouse 2007). Part of scientific literacy is understanding the nature of science (Duschl 2008), which can be revealed, in part, by learning the historical context of current science concepts (Allchin 2013; Bybee et al. 1991).

History of science can be taught using scientific inquiry, scientific argumentation, and authentic experience (Clary and Wandersee 2013) through a variety of methods, including case studies, role playing, debating historic science controversies, and reconstructing significant iconic experiments (such as electrolysis of water, calculating the circumference of the Earth, or constructing a Voltaic battery). This article describes a lesson--Glaciers: As Cold as Ice--that aligns with the Next Generation Science Standards (NGSS Lead States 2013; see box, pp. 59-61) and uses the 5E instructional model.

Engage: Setting the stage

This lesson, requiring three days, touches on the tentative nature of scientific knowledge, both the empirical and subjective nature of science, scientific theory, and understanding how observations relate to inferences (NSTA 2000; NGSS Lead States 2013). Students begin with the Tricky Tracks activity, which involves making observations and inferences about an image of fossil footprints divided into three panels (Figure 1) (National Academies Press 1998, p. 89). The students make observations as they first view only a third of the image, then two-thirds, and eventually the entire image. Students then write a Claim, Evidence, Reason (CER) statement (Figure 2) addressing the question: What occurred at this location? They construct a claim, offer evidence to support the claim, and explain their reasoning about how the evidence supports the claim (McNeill and Krajcik 2008).

[FIGURE 1 OMITTED]

The teacher engages students in discussions about the differences in observations and inferences; how science knowledge can be subjective, depending on a person's perspectives and life experiences; and that science knowledge is refined as additional evidence comes to light. Explicit reflection helps students understand the nature of science (Lederman, Lederman, and Antink 2013).

Explore: Modeling glaciers

Students model glaciers and glacial flow on a small scale with Gak (a polymer made from glue, borax, and water; see "On the web") mixed with small pieces of gravel, and paper towel tubes cut in half, length-wise, to simulate valleys with measurement marks every 1 cm. Students layer two different colors of Gak, like stacks of crackers in a sleeve, tilt up the tube and rest the high end on an object, and watch the polymer flow down the "valley" (Figure 3). Students can use tablets and time-lapse applications (see "On the web") to capture video footage of the flow. Students measure the distance covered and the time elapsed for the flow to reach the bottom and record the data on a collection sheet (see "On the web"), then use the data to calculate the speed of the flow. Students can vary the angle of the glacial valley as well as place small balls of tape on the valley floor or side to simulate irregularity in the terrain and vary the glacial flow.

[FIGURE 3 OMITTED]

Next, students view a time-lapse video (see "On the web") of the Columbia Glacier in Alaska (Balog 2014). Using a graphic organizer (Figure 4, p. 56), students compare their glacier model to a real glacier flow, then discuss the common indicators of glaciers from past glacial flows such as glacial striations, polished rock surfaces, and large boulder and sediment depositions miles from their original sources as well as possible effects of glacial flows on Earth's surface such as carving and shaping "U"-shaped valleys.

Explain: Attaching academic vocabulary

Students draw and label a diagram of a glacier (Figure 5, p. 57), using glacier terminology introduced by the teacher, including end moraine, terminal moraine, lateral moraine, medial moraine, glacial trough, glacial striations, glacial polishing, and glacial flow. …

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