Academic journal article Science Scope

Teaching Electromagnetic Waves: Used in Communication Technologies

Academic journal article Science Scope

Teaching Electromagnetic Waves: Used in Communication Technologies

Article excerpt

Compared to previous national science education standards (AAAS 1993; NRC 1996), which informed many state science standards over the past two decades, the Next Generation Science Standards (NGSS) include a stronger focus on electromagnetic waves in modern communication technologies. In particular, performance expectation MS-PS4-3, which is part of the standard Waves and their Applications in Technologies for Information Transfer (MS-PS4), states, "Integrate qualitative scientific and technical information to support the claim that digitized signals are a more reliable way to encode and transmit information than analog signals" (NGSS Lead States 2013). The clarification statement highlights that the emphasis is on waves used for communication, including the conversion of binary patterns. While it can be challenging to teach such a scientifically complex array of concepts in a manner that is conceptually accessible for middle school students, this article describes an approach that systematically builds student concepts in an interactive and engaged manner while simultaneously incorporating a natural connection to the NGSS crosscutting concept of Systems and System Models.

The instructional ideas expressed in this article should be implemented over a series of lessons, and additional student tasks and instructional experiences would be needed to fully reach the performance-expectation goal. However, the following set of activities could form the core of an instructional sequence addressing this complex topic. These lessons would typically occur after instruction in wave characteristics such as amplitude, frequency, and wavelength, and the concept that waves carry energy--this set of lessons focuses on the concept that waves can also carry information.

Establishing a model

This set of lessons begins by establishing a physical model for using electromagnetic waves in communication technologies. As is recommended in the NGSS crosscutting concept of Systems and System Models, it is helpful to explicitly include in the discussion with students the elements of the model and how these elements are tools for understanding and testing ideas (NGSS Lead States 2013). This supports student development of the crosscutting concept that scientific models are tools for thinking; this physical model will support student thinking about abstract digital wave signals in modern communications. It will also be helpful for supporting the science and engineering practice Developing and Using Models (NGSS Lead States 2013). Among elements of modeling practice specified by NGSS Appendix F for grades 6-8, this particular modeling activity is well suited to support student understanding of developing a model to describe unobservable mechanisms (such as communication signals sent via electromagnetic waves) and using a model to describe phenomena (NGSS Lead States 2013). By explicitly highlighting the aspects of scientific modeling students do in this task, teachers can address the NGSS goal of seamlessly integrating science content with crosscutting concepts and science and engineering practices.

Wearing safety glasses while engaging in this model, students will use a spring to transmit waves. To reduce the number of springs and amount of space necessary, two student groups (four students per group) can share one long (approximately 2 m unstretched) spring, with each group independently using one end. Student "anchors" are stationed back-to-back in the middle of the spring to hold their group's half fixed on the floor (see Figure 1). A spring like this is often called a "snaky spring," costs approximately $12, and is available from many science suppliers. Alternatively, if there are enough springs and space, each group could have its own spring, or students could use a jump rope (which has greater frictional losses on a carpeted floor) or a regular slinky to transmit waves.

[FIGURE 1 OMITTED]

Demonstrate the model by having one student anchor the middle and another student slightly stretch half of the spring. …

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