Grade 8: Earth Science

Here is a comprehensive overview of the Grade 8 Earth Science content, aligned with the British Columbia (BC) Curriculum.

In BC, the Grade 8 Earth Science unit focuses on our planet’s dynamic geology, exploring the powerful forces that shape its surface and interior.

BC Grade 8 Science: Earth Science Unit – Earth’s Geological Processes

This unit explores the questions: “How does the Earth change over time?” and “What powerful forces shape our planet’s landscape?” It moves from the deep interior of the Earth to the surface features we see today.

Overarching Big Ideas (for the Earth Science Unit)

• The theory of plate tectonics is the unifying theory that explains Earth’s geological processes.

• Energy from Earth’s interior drives the rock cycle and creates major geological features.

Core Components of the Grade 8 Earth Science Unit

Part A: Earth’s Interior Structure

• Key Concepts: Layers of the Earth, composition, and physical state.

• Learning Goals:

  • Identify and describe the main layers of the Earth based on composition:

    • Crust (thin, solid outer layer)

    • Mantle (thickest layer, semi-solid, convective flow)

    • Core (composed of a liquid outer core and a solid inner core; the flow of the outer core generates Earth’s magnetic field).

  • Understand that temperature and pressure increase with depth.

Part B: The Theory of Plate Tectonics

• Key Concepts: Continental drift, lithospheric plates, and plate boundaries.

• Learning Goals:

  • Understand that the Earth’s lithosphere (crust and upper mantle) is broken into large, rigid pieces called tectonic plates.

  • Describe the evidence that supports the theory of plate tectonics:

    • The jigsaw-like fit of the continents (e.g., South America and Africa)

    • Fossil evidence

    • Geological evidence (matching mountain ranges and rock layers)

    • The location of earthquakes and volcanoes

  • Identify that the driving force behind plate movement is heat-driven convection currents in the mantle.

Part C: Plate Boundaries and Geological Events

• Key Concepts: The three boundary types and their associated landforms and hazards.

• Learning Goals:

  • Describe the three main types of plate boundaries and the geological events they cause:

    • Divergent Boundary: Plates move apart. Causes mid-ocean ridges, rift valleys, and new crust formation.

    • Convergent Boundary: Plates move together. Causes:

      • Subduction zones, deep-sea trenches, and volcanoes (oceanic-continental collision)

      • Massive mountain ranges like the Himalayas (continental-continental collision)

    • Transform Boundary: Plates slide past one another. Causes earthquakes (e.g., San Andreas Fault).

Part D: The Rock Cycle

• Key Concepts: Igneous, sedimentary, and metamorphic rocks.

• Learning Goals:

  • Explain that the rock cycle is a continuous process by which rocks are formed, broken down, and transformed by Earth’s processes.

  • Classify rocks into three major types based on their formation:

    • Igneous: Formed from the cooling and solidification of magma or lava.

    • Sedimentary: Formed from the compaction and cementation of sediments.

    • Metamorphic: Formed when existing rocks are changed by intense heat and pressure.

Curricular Competencies in Action (The “Doing” of Science)

• Questioning and Predicting:

  • “If the Atlantic Ocean is getting wider, what must be happening to the Pacific Ocean?”

  • “Why are there volcanoes on the west coast of BC but not on the east coast?”

• Planning and Conducting:

  • Lab: Modeling Convection Currents. Use a transparent container of water and a heat source (with food colouring) to model how heat from the Earth’s core creates convection currents in the mantle that can move plates.

  • Activity: Edible Rock Cycle. Use different candies to model the processes of the rock cycle (e.g., smashing for weathering, melting and re-solidifying for igneous rock, pressing together for sedimentary).

• Processing and Analyzing Data and Information:

  • Analyze a map of the world’s tectonic plates, volcanoes, and earthquake zones to identify and label the different types of plate boundaries.

  • Classify various rock samples as igneous, sedimentary, or metamorphic based on their observable characteristics.

• Evaluating:

  • Evaluate different models of the Earth’s interior (e.g., a hard-boiled egg model vs. a peach pit model) and discuss their strengths and limitations.

• Applying and Innovating:

  • Contribute to care for self, others, and community by researching and creating an emergency preparedness plan for a specific geological hazard (e.g., an earthquake in BC).

• Communicating:

  • Create a diagram or a storyboard that illustrates the journey of a rock through the complete rock cycle.

Sample Learning Standards from the BC Curriculum

• Content: “Explain the theory of plate tectonics.”

• Content: “Explain how the rock cycle is a result of interactions between the tectonic plates and the hydrologic cycle.”

• Content: “Analyze the role of the rock cycle in the formation of igneous, sedimentary, and metamorphic rocks.”

• Curricular Competency: “Experience and interpret the local environment.” (e.g., observing local rock types or landforms shaped by geological processes).

Key Connections to Other Grade 8 Science Units

• Connection to Physics (Energy): The concept of thermal energy from the Earth’s core is the engine that drives plate tectonics through convection currents.

• Connection to Chemistry: The formation of minerals and rocks involves chemical processes and the arrangement of elements. The composition of the Earth’s layers is a chemical concept.

• Connection to Biology: Geological processes create and shape the habitats and landforms (mountains, valleys, islands) where life exists.

This unit provides a foundational understanding of the dynamic planet we live on, helping students see the landscape not as static, but as a snapshot in a continuous process of change driven by immense forces from within the Earth.