Academic journal article Journal of Geoscience Education

Seventh Grade Students Learn about the Use of Clays in Everyday Products

Academic journal article Journal of Geoscience Education

Seventh Grade Students Learn about the Use of Clays in Everyday Products

Article excerpt


Clay minerals are widespread at the Earth's surface, compose a large percentage of sedimentary rocks, and are important components of many common products including brick and tile, tableware, sanitaryware, paper, paints, plastics, rubber, cosmetics, and pharmaceuticals. Knowledge of the role of clay industrial products supports attainment of science knowledge goals in middle school (Rule and Guggenheim, 2007).

This simple pretest-intervention posttest study presents effective examples of clay science activities for middle school students that highlight the multiple uses of clay minerals in common products and support learning of other geoscience concepts such as crystal structure and resulting physical properties of materials. A class of twenty-one students at an urban middle school in central New York State participated in the study. Student scores on the pretest averaged 52% correct compared to 83% correct on the posttest taken seven weeks later, indicating the efficacy of the activities in teaching clay science concepts. A written survey three weeks after lessons had concluded showed students learned much about clay properties and clay use in everyday objects along with enjoying group work and the hands-on materials with clues.


Importance of Studying Clay - Clay minerals are the most abundant minerals at the Earth's surface, being major components of soils (determining many soil properties) and sedimentary rocks, along with blanketing much of the world s ocean floor (Moore & Reynolds, 1997). Clay minerals are important in many geological applications including correlation of stratigraphic sections, determination of environments of deposition and temperature indicators for generation of hydrocarbons (Murray, 1999). Most clay minerals are the chemical weathering products of feldspars and other silicate minerals that formed deep within the Earth. When these minerals interact with the earth's atmosphere under cooler and lower pressure conditions, they weather to form more stable clay minerals. These new hydrated alumino silicates generally have very tiny crystals on the same size order as cigarette smoke particles or viruses. This small size, along with other properties such as platy shape and absorption of water between particles resulting in plasticity, makes them ideal for many industrial applications.

Clays have been used from prehistoric times in brick and tile construction and for pottery. Kaolin clays are used extensively in the paper industry to produce a bright white, non-porous matte to glossy surface that accepts ink. They are also used in ceramics and as fillers in rubber, plastics, and paints. Because of electrical, thermal, and ultraviolet light resistance, talc is used in porcelain electrical fixtures and as filler for plastics used to make computer housing, lawn furniture and dashboards. Smectite clays are used in cat litter, drilling muds, foundry sand, wine and oil clarification, and for pelletizing iron ore (Odom, 1984). A variety of clay minerals contribute to the cosmetics industry, being used in medicine tablets, toothpaste, lipstick, eye makeup, face powder, and facial masks. New processing techniques of the future will likely result in improved clay products that utilize engineered pillared clays, nanocomposites and organoclays (Murray, 1999). Because clays play such an important part in everyday products, students need to have basic understandings of these valuable minerals.

Clay Science Supports Learning of Geoscience Principles - Rule and Guggenheim (2007) suggested a standards-based clay science curriculum for prekindergarten through high school students. The inclusion of clay science topics in the middle school geoscience curriculum helps students understand that clay minerals play a large role in the rock cycle. They are major constituents and cements in sedimentary rocks, occur as foliated minerals in metamorphic rocks, and are present, most notably as micas, in igneous rocks. …

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