Extending Scientific Discussion

This chapter emphasizes the importance of building on learning progressions as they unfold over the course of several school years. Learning progressions can also take place in the short term as the ideas and concepts related to specific science activities are extended and deepened.

For example, in Ms. Winter’s classroom, the Mystery Box activity eventually led to an investigation of the different objects in the classroom that were made of wood, plastic, or metal. The students, working in pairs, focused on each type of material and attempted to catalog, using pictures or words, all of the objects they could identify that were made of that material. When two or more of the same objects were identified, such as chairs, the students counted and recorded the total number of those objects.

At group meeting time, for a period of several days, the students reported on their findings. Questions arose that led to further investigation. Had each student pair identified the same items? Was there agreement or disagreement about some items? What did all of the wooden items have in common, and in what ways did they differ? How could the students tell, for sure, if something was made of wood?

The students requested magnifying glasses in order to see the grain of certain items better, and Ms. Winter introduced a set of “density blocks,” which were same-sized cubes and triangular prisms made out of different materials (wood, plastic, metal). This led to several weighing and measuring activities that involved using a pan balance and a water displacement cup (sometimes called a “Eureka can”). This allowed the students to begin the transition away from reliance on sensory observations (felt weight) and to see the need for standard measurement—critical developments that are frequently overlooked or underestimated in science curricula and instruction. The students explored weight versus volume, and they made predictions about whether the weight of the triangular prisms would match the rank ordering of weight of the cubes—that is, whether the metal triangular prism would be heavier than both the wooden and plastic ones, and why that might be.

This is an example of just one of many ways the Mystery Box activity could be extended to allow students more time to work with complex ideas across different contexts—an integral and essential part of learning progressions. Students themselves might generate questions about the materials that would be worthy of investigation. The teacher might engage the students in a discussion about the

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