Earth and Environmental Science 11–12 · Year 11
What drives the plates: a pupil model of slab pull, ridge push and mantle drag
Module 3: Energy Transformations
The idea
A cold, dense slab sinking at a subduction zone pulls the rest of the plate after it, and plate speeds show that this pull matters more than ridge push or mantle drag.
Safety card
Hazards
- learners pulled off balance
- tripping in a crowded space
Controls
- gentle, slow pulls and pushes only
- a clear, open floor
- learners may opt out of linking arms
Note
No hazardous chemicals or heat sources: record the activity in the school's RiskAssess risk assessment, following the NSW Department of Education Science safety and compliance page; the Chemical Safety in Schools package is not triggered.
What you need
- an open space and a line of about seven learners (Earthlearningidea What drives the plates?)
- a world plate map showing subduction zones with their triangular teeth
- string or a map measurer and a ruler to measure plate-margin lengths
- the Earthlearningidea evidence sheet What drives the plates? The evidence
How to do it
- Two learners stand together as the two plate margins at an oceanic ridge; about five others link arms beside one of them to form a pupil plate.
- Model mantle drag: the teacher walks behind the line from the ridge end, nudging each learner’s back; record how far the plate moves.
- Model ridge push: push gently between the two ridge learners; record how far the plate moves.
- Model slab pull: pull the learner at the far end of the line gently; record how far the whole plate moves.
- On the plate map, measure the total margin and the subducting margin of the Pacific, Nazca and South American plates, calculate the percentage subducting and compare it with their speeds.
What you should see
In the pupil model the nudges (mantle drag) and the push at the ridge move the linked line little, while pulling the end learner drags the whole plate, the result Earthlearningidea uses to show slab pull as the largest force. On the map the Pacific plate has about a third of its margin subducting and moves fastest, the Nazca plate about a quarter and moves at a speed between the two, and the South American plate has no subducting margin and moves slowly (Earthlearningidea), the pattern expected if slab pull drives the plates.
What changes
- What you change
- force modelled (mantle drag, ridge push or slab pull); percentage of subducting margin
- What you measure
- movement of the pupil plate; plate speed
- What you keep the same
- same line of learners
- same size of push or pull
- same map for measuring margins
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Mantle convection drags the plates along like a conveyor belt (drag is minor next to slab pull).
- The mantle is molten (it is solid rock that flows very slowly).
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Earth and Environmental Science Stage 6 Syllabus (2017), NESA; current, replaced by the 11–12 Syllabus (2025) from 2028EES11-10EES11-9EES11/12-5EES11/12-6EES11/12-7
- Earth and Environmental Science 11–12 Syllabus (2025), NESA; to be implemented from 2028, not yet taughtEES-11-01
- Australian Curriculum v9No Australian Curriculum v9 code is listed.
Sources
The pages the author read to write this activity.