Activity 01
Play-Doh Earth Model
Students use different colours of modelling clay to create a scale model of the Earth's layers. They build the model from the inside out, finishing with a thin crust, which helps reinforce the sequence and relative thickness of each layer.
Identify the four main layers of the Earth and describe one key characteristic of each.
Facilitation TipProvide students with a table of scaled radii for each layer to ensure their models are proportionally accurate.
What to look forUse an 'exit ticket' where students must draw a labelled diagram of the Earth's layers and write one key fact for each layer before leaving the lesson.
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Activity 02
Seismic Slinky Waves
Using a Slinky spring, students demonstrate the difference between P-waves (longitudinal compressions) and S-waves (transverse waves). This physical model helps them understand why S-waves cannot travel through the liquid outer core.
Explain how scientists use seismic waves to infer the structure of the Earth's interior.
Facilitation TipChallenge groups to show what happens when a wave hits a boundary between two different media, simulating reflection and refraction.
What to look forA short test with structured questions, including interpreting a diagram showing seismic wave paths to explain why the outer core must be liquid.
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Activity 03
Density Column Investigation
Students carefully pour different liquids with varying densities (like syrup, water, and oil) into a measuring cylinder to create a layered column. This serves as an analogy for how the Earth's materials settled into layers based on their density.
Compare the composition and state of the inner core with the outer core.
Facilitation TipAsk students to predict the order of the layers before they begin, reinforcing the concept of density.
What to look forStudents use a rubric to assess their own physical model of the Earth, checking for correct layering, proportional sizing, and accurate labels.
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Generate Complete Lesson→A few notes on teaching this unit
Start with the familiar, the crust we live on, and use analogies like a hard-boiled egg to introduce the concept of distinct layers. Physical models, whether with modelling clay or density columns, are essential for making these abstract ideas concrete. Continually reinforce the idea that this is a scientific model built on indirect evidence, not direct observation, which is a cornerstone of how much of science operates.
By the end of these activities, students will be able to construct a model of the Earth's interior and confidently explain how seismic data provides the crucial evidence for its structure and composition.
Watch Out for These Misconceptions
The Earth's mantle is a layer of liquid magma.
The mantle is almost entirely solid rock. However, it is so hot that it can flow very slowly over millions of years, a property known as plasticity. Magma is only formed in specific, localised pockets in the upper mantle or crust.
Scientists have drilled down to the mantle and core to see what they are like.
The deepest hole ever drilled is only about 12.2 km deep, which barely scratches the surface of the crust. All our knowledge about the mantle and core comes from indirect evidence, primarily by studying how earthquake waves travel through the Earth.
The Earth's core is hollow or contains a hidden world.
Scientific evidence from seismic waves and gravity measurements shows that the Earth's core is its densest part. It consists of a solid inner core and a liquid outer core, both made primarily of iron and nickel.
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