Provide samples, and ask students to relate igneous rock texture to the formational history. Have students classify and name unlabelled igneous rocks using texture, colour, and composition data. Use the chart Percent Mineral Composition of Igneous Rocks typically provided on the provincial exam. Challenge students to produce an illustrated glossary or models of types of volcanoes and other igneous features and structures, and make a presentation to the class. The number of new terms and concepts in the organizer suggests a need for frequent review strategies.
Students identify igneous rock specimens using a simplified classification chart.
Note how consistently they look for crystal size and mineral composition and appropriately interpret the chart to determine the rock name. Assess their abilities to relate the overall colour of non-glassy volcanic rocks to composition. Check students' knowledge of the relationship between magma composition and characteristics by having them characterize each end of the silicic mafic continuum. Ask students to explain how a single magma chamber can release magma of different compositions in separate eruptions. Assess their explanations based on variety, plausibility, and appropriate application of Bowen's reaction series.