Content Knowledge for Teaching about Matter

Learning about matter serves as a critical foundation for understanding many other scientific ideas. Understanding what matter is, forms in which it exists, properties of matter, and conservation of matter in the elementary grades supports students in being able to explain a variety of phenomena including melting and freezing, as well as larger processes such as the water cycle. However, despite its importance as a foundation for science learning, the concept of matter is both complex to teach and difficult to learn (Talanquer, 2009; Tsarpalis & Sevian, 2013). In particular, addressing the idea that “matter exists as particles that are too small to see” (rather than identifying specific particles such as atoms) at the elementary level places new demands on elementary teachers to determine how and when to develop students’ understanding of this matter concept to explain real-world phenomena.  

By identifying core concepts related to a matter, we can begin to articulate specific elements of teachers' CKT as those ideas intersect with the Work of Teaching Science framework. For example, elementary students learn about matter —its structures and properties, the physical and chemical changes it undergoes, and the particles that make it up. Investigations can be carried out to observe, measure, and identify various materials according to their properties, such as reflectiveness, color, and hardness. This topic area targets reversible and irreversible changes that happen to materials from heating, cooling, and mixing of substances. Evidence can be used to categorize changes such as those observed when (a) heating butter or an egg, or (b) freezing water or a leaf. Investigations address whether substances that interact in a chemical reaction become new substances with different properties. Evidence from these investigations can support an argument that the overall weight of the materials is conserved regardless of what change occurs, including the apparent disappearance of materials. Learning about matter also includes the idea that objects are made of small pieces that can be taken apart and recombined to form a new object and the idea that all matter consists of particles that are so small as to be invisible. Students are expected to develop a particle model that could explain why adding an invisible gas to a balloon increases its volume, or sugar added to a glass of water seems to disappear.

If we map each of these content ideas onto the various instructional tools in the Work of Teaching Science framework, we can identify specific elements of teachers’ CKT related to the teaching of matter, as shown below.