Unit Overview
6.4 Rock Cycling & Plate Tectonics*

How and why does Earth's surface change?*

Unit Summary

*This unit is still being revised based on the feedback from the field test.
Mountains move! And there are ocean fossils on top of Mt. Everest! In this plate tectonics and rock cycling unit, students come to see that the Earth is much more active and alive than they have thought before. The unit launches with documentation of a 2015 Himalayan earthquake that shifted Mt. Everest suddenly to the southwest direction. Students also discover that Mt. Everest is steadily moving to the northeast every year and getting taller as well. Students wonder what could cause an entire mountain to move--all the time in one direction and backwards during an earthquake.

Students investigate other locations that are known to have earthquakes and they notice landforms, such as mountains and ridges that correspond to earthquake patterns. They read texts, explore earthquake and landform patterns using a data visualization tool, and study GPS data at these locations. Students develop an Earth model and study mantle convection motion to explain how Earth’s surface could move from processes below the surface. From this, students develop models to explain different ways plates collide and spread apart, ultimately explaining how Mt. Everest could move all the time in one direction, and also suddenly, in a backward motion, during an earthquake.

At this point, students also find out that climbers on Mt. Everest found evidence of marine fossils near the top of the mountain. Using ideas from plate tectonics and uplift, along with ideas about how fossils form, how they are uplifted, and how they are exposed through weathering and erosion, students develop a time series model that traces a marine fossil from an ancient sea bed to the top of the world’s highest peak. Students explain how ancient rock layers and fossils were exposed over time by weathering and erosion.

*This unit is scheduled to be released publicly in October 2021. The information on this page may be adjusted slightly as the developers revise the unit.

Additional Unit Information

Building Toward the Following Standards and Practices
Performance Expectations

This unit builds towards the following NGSS Performance Expectations (PEs): 

  • MS-ESS1-4: Construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organize Earth’s 4.6-billion-year-old history. 
  • MS-ESS2-1: Develop a model to describe the cycling of Earth’s materials and the flow of energy that drives this process.
  • MS-ESS2-2: Construct an explanation based on evidence for how geoscience processes have changed Earth’s surface at varying time and spatial scales.
  • MS-ESS2-3: Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
Disciplinary Core Ideas

ESS1.C: The History of Planet Earth

  • The geologic time scale interpreted from rock strata provides a way to organize Earth’s history. Analyses of rock strata and the fossil record provide only relative dates, not an absolute scale. (MS‑ESS1‑4)
  • Tectonic processes continually generate new ocean seafloor at ridges and destroy old seafloor at trenches. (HS.ESS1.C GBE) (secondary to MS‑ESS2‑3)

ESS2.A: Earth’s Materials and Systems

  • All Earth processes are the result of energy flowing and matter cycling within and among the planet’s systems. This energy is derived from the sun and Earth’s hot interior. The energy that flows and the matter that cycles produce chemical and physical changes in Earth’s materials and living organisms. (MS‑ESS2‑1)
  • The planet’s systems interact over scales that range from microscopic to global in size, and they operate over fractions of a second to billions of years. These interactions have shaped Earth’s history and will determine its future. (MS‑ESS2‑2)

ESS2.B: Plate Tectonics and Large-Scale System Interactions

  • Maps of ancient land and water patterns, based on investigations of rocks and fossils, make clear how Earth’s plates have moved great distances, collided, and spread apart. (MS‑ESS2‑3)

ESS2.C: The Roles of Water in Earth’s Surface Processes

  • Water’s movements—both on land and underground—cause weathering and erosion, which change the land’s surface features and create underground formations. (MS‑ESS2‑2)
Focal Science & Engineering Practices

While this unit engages students in multiple SEPs across the lesson level performance expectations for all the lessons in the unit, there are four focal practices that this unit targets to support students’ development:

  • Developing & Using Models
  • Using Mathematics & Computational Thinking
  • Constructing Explanations and Designing Solutions
Focal Crosscutting Concepts
  • Patterns
  • Cause and Effect
  • Scale, Proportion, and Quantity
  • Stability and Change
Unit Information
What are prerequisite math concepts necessary for the unit?

This unit exposes students to movement data using different measurements and time scales, and, importantly, the movement of two objects in relationship to one another. Students wrestle with GPS movement data in different directions and also visualizing the depth and breadth of earthquake patterns using a visualization tool. Prerequisite math concepts that may be helpful include:

  • CCSS.Math.Content.4.MD.A.1 Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table. 
  • CCSS.MATH.CONTENT.5.MD.A.1 Convert among different-sized standard measurement units within a given measurement system (e.g., convert 5 cm to 0.05 m) and use these conversions in solving multi-step, real world problems.
  • CCSS.Math.Content.5.NBT.A.3 Read, write, and compare decimals to thousandths.
  • CCSS.Math.Content.5.NBT.A.4 Use place value understanding to round decimals to any place.
  • CCSS.Math.Content.6.RP.A.2 Understand the concept of a unit rate a/b associated with a ratio a:b with b ≠ 0, and use rate language in the context of a ratio relationship. 

It is important to note that this unit is reinforcing some elementary mathematics standards in a new context and using scales at which students may have not considered before; thus, we anticipate that while some of the mathematics in this unit is aligned to upper elementary math development, it may be a new challenging context for students to apply the mathematics ideas. 

What modifications will I need to make if this unit is taught out of sequence?

This is the fourth unit in 6th grade in the OpenSciEd Scope and Sequence. Given this placement, several modifications would need to be made if teaching this unit earlier or later in the middle school curriculum. These include:

  • If taught before OpenSciEd Unit 6.3, students will not have developed ideas about convection as a means that energy is transferred in fluids. This idea is developed and built upon in Unit 6.3, so this unit only has one lesson to map ideas of convection in the mantle to the movement of the plates on the surface, but does not build any kind of particle level explanation of convection. 
  • If this unit is taught after OpenSciEd Unit 7.1, the chemical weathering component could be expanded to include chemical processes that weather rock. 
What are some common ideas that students might have?

Students will be challenged in this unit to think about processes that occur on very long time scales and also at very large spatial scales. This will likely be the first time they have thought about Earth system processes happening on scales this large–so large they are really hard to even imagine. Students will likely bring with them some knowledge of different geological time periods (e.g., Triassic and Jurassic time = time of the dinosaurs), but it is really not important for them to know the different names and time periods on a geological time scale. This unit challenges students to think conceptually about how long these processes take to occur, but they will not be asked to identify or name time periods. 

To represent these spatial scale ideas students will transition between top-down perspectives and cross-section perspectives to represent movement of the mantle and the plates of Earth’s crust. Some students may readily come to class with a cross-section perspective, but likely many students will need guidance on drawing cross-sections, at least initially. 

Many students may come to the unit with some ideas about “plates” and “plate tectonics.” It is common for students to think that the continents are the plates and they “float” around slowly in the ocean. This unit purposely uses a map with ocean floor topography (called bathymetry) to help students visualize that the bottom of the ocean is part of Earth’s crust too, as the ocean has “plates” that move as well, and many plates include parts of continents and parts of ocean floors.  

Finally, many students may come to the unit thinking the inside of the Earth is liquid lava. This is because all the images they see of hot stuff coming out of the Earth is liquified rock, in the form of lava. In actuality,  the mantle is made of molten rock that is more solid than liquid, but it behaves as a very thick semi-solid, similar to putty. This unit uses fluids to demonstrate convection, but it is important to emphasize to students that the inside of the Earth is not fluid lava. Because  we cannot replicate the movement of solids at really, really high temperatures, we utilize fluids like water and oil, because they show convection at lower temperatures.