Academic journal article Teaching Science

An Evidence-Based Approach to Teaching Plate Tectonics in High School

Academic journal article Teaching Science

An Evidence-Based Approach to Teaching Plate Tectonics in High School

Article excerpt

INTRODUCTION

One of the richest and most engaging concepts in Earth and environmental science is plate tectonics and it is covered in the Australian Curriculum in Year 9 earth and space sciences. The relevant science understanding content description is "The theory of plate tectonics explains global patterns of geological activity and continental movement" (ACARA, 2019a, ACSSU180). The elaborations to ACSSU180 are:

1. recognising the major plates on a world map;

2. modelling sea-floor spreading;

3. relating the occurrence of earthquakes and volcanic activity to constructive and destructive plate boundaries;

4. considering the role of heat energy and convection currents in the movement of tectonic plates; and

5. relating the extreme age and stability of a large part of the Australian continent to its plate tectonic history.

The problem with this list is the fourth elaboration, because the idea that convection currents in the mantle drive the movement of tectonic plates is a myth. This convection is presented as whole mantle or whole asthenosphere cells with hot material rising under the Earth's divergent plate boundaries and cooler material sinking at the convergent boundaries with the lithosphere dragged along by the horizontal flow of the asthenosphere (Figure 1). This was the preferred explanation for plate motion until the early 1990s but it does not stand up to a frequent deduction made by Year 9 students: how can there be large-scale mantle convection if hotspots (like Hawaii) don't move? Most science teachers quickly cover convection as the mechanism driving plate tectonics and focus on teaching the structure of the Earth, the evidence for plate movement, descriptions of the types of boundaries, and the earthquakes, tsunamis and volcanoes associated with them. A rich teaching and learning experience is lost if plate tectonic processes are reduced to description, rather than evidence-based science.

Science students get a chance to go into greater depth on the topic of plate tectonics if they choose Earth and environmental science in Year 11 and 12. In Unit 2: 'Earth processes--energy transfers and transformations', the "Students examine how the transfer and transformation of heat and gravitational energy in Earth's interior drive movements of Earth's tectonic plates" (ACARA, 2019b). The Science Understanding content description in Unit 2 relevant to plate tectonics is "Transfers and transformations of heat and gravitational energy in Earth's interior drives the movement of tectonic plates through processes including mantle convection, plume formation and slab sinking" (ACARA, 2019b, ACSES047). This gives the teacher greater scope to guide students through the fascinating complexities of plate tectonics but still emphasises mantle convection as the dominant mechanism driving plate motion.

This article proposes an evidence-based approach to teaching the mechanisms driving the movement of tectonic plates that should lead students towards the prevalent explanation appearing in peer-reviewed science journals and taught in universities. This has been trialled successfully with Year 9 science and Year 11 EES classes. It is much more engaging because it allows students to build an internally consistent, complete, and satisfying picture of plate tectonics.

POSSIBLE DRIVING MECHANISMS FOR PLATE MOTION

The starting point for students to gain an evidence-based explanation of plate motion is to present the three possible mechanisms for driving the motion of tectonic plates: mantle convection, ridge push and slab pull.

Mantle convection: Convection is driven by heat from the core and involves either the whole mantle or convections cells within the plastic asthenosphere (Figure 1). The upwelling in the convection cells occurs under the Earth's divergent plate boundaries, and cooler material sinks at the convergent boundaries. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.