Page 234 - Big Ideas Year 10 sciPAD 2025

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234 SCIPAD - BIG IDEAS - BOOK 2
EARTH SYSTEMS
How Tectonic Plates Move
Tectonic plates float on a layer of molten (liquid) rock - the mantle. The mantle near the core is
much hotter than the mantle near the crust. This hot mantle expands, becomes less dense and
rises. Mantle near the crust cools and becomes denser and sinks.
This temperature difference sets up convection currents and causes the movement of the tectonic
plates.
1. Using information from “Inside the Earth” on a previous page, state the:
(a) Temperature of the lower mantle (near the core): °C
(b) Temperature of the upper mantle (near the crust): °C
2. State what happens to the mantle near the core. 
3. State what happens to the mantle near the crust. 
4. What is the name given to currents in fluids created by the rise and fall of materials when
they are heated and cooled? 
Observing Convection
Aim: To observe convection currents caused when two fluids at
different temperatures interact.
Equipment: Large transparent cylinder or beaker big enough to
contain a small conical flask- hot and cold tap water -
red and blue food colouring - scissor tongs.
Method: 1. Fill the large cylinder (beaker) with cold tap water. Leave
some space at the top so it doesn’t spill over.
2. Fill the conical flask with hot tap water.
3. Add a few drops of red food colouring to the hot water
in the conical flask. Allow the food colouring to evenly
disperse.
3. Use the tongs to carefully lower the conical flask into the
large container.
4. Observe the coloured liquid.
Observations: 



Explanation: 


M
A
N
T
L
E
C
O
R
E
Converging
plates
(subduction zone)
Plate sinks into
the subduction
zone
Convection
cell
Plates are carried on the
currents created in the mantle
Diverging plates
(mid-ocean ridge)