Cracking the Ocean Floor: Seafloor Spreading and Plate Tectonics

Shared by A STEM Educator

6th GradeNGSS Phenomenon-BasedMS-ESS2-1, MS-ESS2-2, MS-ESS3-245 min

Learning Objective

Students will develop and use models to explain how seafloor spreading drives plate motion (ESS2.B), analyze magnetic striping and sediment age data as evidence for continental drift, and apply their understanding to evaluate real-world sites for geothermal energy and earthquake early-warning infrastructure.

Lesson Overview

Students investigate the puzzling match between South America and Africa's coastlines, then analyze earthquake/volcano distributions and ocean-floor magnetic striping data to build a model of plate tectonics and seafloor spreading. Lesson connects to earthquake early-warning system design and geothermal energy site selection.

Materials

Printed outline maps of South America and Africa (one per pair)
Scissors and tape
World map showing earthquake epicenters and volcano locations (class set)
Colored pencils (red, blue, green, orange)
Printed ocean-floor magnetic striping data strips (one per group of 4)
Rulers (metric)
Calculators
Student investigation handout (one per student)
Four-Quadrant note sheet (one per student)
Exit slip slips (half-sheet, one per student)
Chart paper and markers for VNPS boards

Scaffolded Task Progression

1Task 1

Earthquake Early-Warning Site Mapping (Floor) You are on a team designing an earthquake early-warning sensor network. Using the world map provided, plot the following earthquake epicenter locations with a red dot and volcano locations with an orange triangle. Then draw a blue line connecting clusters to outline the plate boundaries you can see. Earthquake clusters to mark: Pacific Rim (ring shape around Pacific Ocean), Mid-Atlantic Ridge (down the center of the Atlantic), Himalayan belt (southern Asia). Volcano clusters to mark: Cascades (western North America), Andes (western South America), Iceland (mid-Atlantic), Indonesia arc. After plotting, answer:
(a) Where would you place earthquake early-warning sensors to protect the most people? Name two specific regions.(b) What pattern do earthquake and volcano locations share?

2Task 2

Boundary Type Classification and Early-Warning Design (Developing)

Not all plate boundaries are the same. Use the descriptions below to label each boundary type on your map with a letter code, then answer the design questions.

- D (Divergent): Plates pull apart; new crust forms; mid-ocean ridges and rift valleys. Example: Mid-Atlantic Ridge, East African Rift.
- C (Convergent): Plates collide; one may subduct under the other; deep trenches, volcanoes, mountain ranges. Example: Cascadia, Andes, Himalayas.
- T (Transform): Plates slide sideways past each other; no crust created or destroyed. Example: San Andreas Fault.

Design Questions:
1. An earthquake early-warning system needs sensors where large, sudden plate movements happen. Which boundary type(s) are highest priority? Explain using evidence from your map.
2. A geothermal energy company wants to drill where Earth's heat is closest to the surface. Which boundary type offers the best opportunity? Why?

Unlock the full lesson

See all 4 scaffolded tasks, the full answer key, warm-up, exit slip, and a print-ready version — free to start.

Create a free account

Already have an account? Sign in

Make it your own

Like this lesson but want to tweak it?

Make an editable copy and adjust the tasks, warm-up, and answer key to fit your class — no need to start from scratch.

Generate a new lesson