Use this diagram to test your knowledge of Earth's internal structure, from the crust down to the inner core.

Let's solve this worksheet step by step.

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🔍 Objective:

Identify each layer and sub-layer of the Earth by matching the numbered labels (1 to 11) on the diagrams with the correct layer names listed at the bottom.

We are given two diagrams:
1. A cross-section of the Earth showing layers from the outside in.
2. A detailed wedge-shaped cross-section showing more sub-layers.

We need to match the numbers (1–11) to the correct layer names.

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🌍 Earth’s Layers (From Outermost to Innermost):

Here is a quick refresher:

1. Crust – Thin outermost solid layer.
2. Mantle – Thick layer beneath the crust, divided into:
- Upper Mantle (includes the Asthenosphere and Lithosphere)
- Lower Mantle
3. Core – Central part, divided into:
- Outer Core – Liquid
- Inner Core – Solid

Also:
- Lithosphere = Crust + Uppermost solid part of the mantle.
- Asthenosphere = Part of the upper mantle that is semi-fluid and allows tectonic plates to move.

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Now let’s identify each number:

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🔹 Diagram 1 (Top Sphere)

This shows a simplified version of Earth’s layers.

- 1: Points to the innermost circle → Inner Core
- 2: Next layer around it → Outer Core
- 3: Layer above the core → Mantle
- 4: Outermost layer → Crust

✔ So far:
- 1 → Inner Core
- 2 → Outer Core
- 3 → Mantle
- 4 → Crust

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🔹 Diagram 2 (Wedge-Shaped Cross-Section)

This shows more detail.

Let’s go from top to bottom (outermost to innermost):

- 5: Topmost layer → Crust
- 6: Just below the crust → This is the uppermost solid mantle, part of the Lithosphere
- 7: Below the lithosphere → Asthenosphere (part of the upper mantle)
- 8: The rest of the upper mantle → Upper Mantle (but note: Asthenosphere is within the upper mantle)
- 9: Lower part of the mantle → Lower Mantle
- 10: Above the inner core → Outer Core
- 11: Center → Inner Core

Wait — we have to be careful here. Let's re-analyze.

Looking at the structure:

- The Lithosphere includes the crust + uppermost solid mantle → so 5 and 6 together make up the lithosphere.
- But 6 is labeled separately, and it's just below the crust → so 6 = uppermost solid mantle, which is part of the lithosphere.

So now assign:

- 5 → Crust
- 6 → Uppermost solid mantle → part of Lithosphere
- 7 → Asthenosphere (plastic-like part of upper mantle)
- 8 → Rest of the upper mantle? Or is it lower mantle?

Wait — there are two layers below the asthenosphere:
- 8 → likely Lower Mantle
- 9 → ??? Wait — no, let’s count properly.

Actually, looking at the diagram:

The layers from top to bottom:

1. 5 → Crust
2. 6 → Lithosphere (but only the mantle part, so uppermost solid mantle)
3. 7 → Asthenosphere (soft, flowing part of upper mantle)
4. 8 → Upper Mantle (the rest of the upper mantle?)
But wait — Asthenosphere is part of the upper mantle, so 7 and 8 might both be parts of Upper Mantle.

But look: the label 8 is pointing to a thick layer beneath the asthenosphere.

Let’s think differently.

Standard division:

- Crust → 5
- Upper Mantle → includes:
- Lithosphere (crust + upper solid mantle) → 5 + 6
- Asthenosphere → 7
- Then the rest of the upper mantle → 8?
- Then Lower Mantle → 9
- Outer Core → 10
- Inner Core → 11

But wait — the lithosphere is defined as Crust + Uppermost solid mantle, so 5 and 6 together form the lithosphere.

But 6 is labeled separately — so 6 = uppermost solid mantle → part of lithosphere.

So:

- 5 → Crust
- 6 → Uppermost solid mantle → Lithosphere (part of it)
- 7 → Asthenosphere
- 8 → Upper Mantle (rest of it, but actually, asthenosphere is part of upper mantle, so 7 and 8 may both be Upper Mantle?)

Wait — no, 7 is Asthenosphere, which is a sub-layer of the Upper Mantle.

So the Upper Mantle includes:
- Lithosphere (solid)
- Asthenosphere (semi-fluid)

So Upper Mantle = 6 (solid part) + 7 (asthenosphere) — but 6 is already labeled.

But in the key, Upper Mantle is a separate option.

So perhaps:

- 6 → Upper Mantle (but only the solid part)?
No — 6 is just the uppermost solid mantle, which is part of the Upper Mantle.

But the Upper Mantle includes both solid and soft parts.

Let’s look at the numbered labels again:

- 7 → points to the layer below the lithosphere (which is 6) → this is the Asthenosphere
- 8 → layer below asthenosphere → Lower Mantle?
Wait — no, the lower mantle is deeper.

But the mantle has two main parts:
- Upper Mantle (including lithosphere and asthenosphere)
- Lower Mantle

So after 7 (Asthenosphere), the next layer should be Lower Mantle?

But then 8 → Lower Mantle?

Then 9 → Outer Core?

Wait — let’s check the depth order.

From top to bottom:

1. 5 → Crust
2. 6 → Uppermost solid mantle → part of Lithosphere
3. 7 → Asthenosphere → part of Upper Mantle
4. 8 → Remaining part of Upper Mantle?
But Upper Mantle is usually considered one layer, but can be subdivided.

But in this diagram, 7 and 8 seem to be both part of the Upper Mantle, but 7 is specifically Asthenosphere.

Then 9 → Lower Mantle

Then 10 → Outer Core

Then 11 → Inner Core

Yes! That makes sense.

So final assignment:

| Number | Layer Name |
|--------|------------------------|
| 1 | Inner Core |
| 2 | Outer Core |
| 3 | Mantle |
| 4 | Crust |
| 5 | Crust |
| 6 | Lithosphere (Crust + Uppermost solid mantle) → But 6 is only the mantle part of lithosphere → so 6 = Uppermost solid mantle → part of Lithosphere |
| 7 | Asthenosphere |
| 8 | Upper Mantle |
| 9 | Lower Mantle |
| 10 | Outer Core |
| 11 | Inner Core |

Wait — 6 is not Lithosphere, because Lithosphere includes crust + upper solid mantle, and 5 is crust, 6 is upper solid mantle → so 5 + 6 = Lithosphere

So Lithosphere corresponds to 5 and 6 together.

But the question says: "write the right numbers in the circles" for each layer.

So we need to match each number to the correct layer name.

Let’s go through the list of options:

✔ Match Numbers to Layers:

- 1 → Inner Core
- 2 → Outer Core
- 3 → Mantle (this is the whole mantle, including upper and lower)
- 4 → Crust
- 5 → Crust
- 6 → Uppermost solid mantle → part of Lithosphere → so 6 → Lithosphere? No, 6 is only the mantle part, but Lithosphere is Crust + that part → so Lithosphere = 5 + 6

But the task is to write the numbers in the circles next to the layer names.

So we need to fill in:

- Mantle → which numbers?
- Lower Mantle → ?
- Inner Core → ?
- etc.

Wait — the instruction says: “Identify each layer and sub-layer... by writing the right numbers in the circles.”

And below, there are blank circles next to each layer name.

So we must fill in the number(s) that correspond to each layer.

Let’s do that.

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✔ Final Matching:

#### Crust
- 4 and 5 → both point to crust
- So Crust → 4 and 5

#### Mantle
- The entire mantle layer → 3 (in first diagram) and also includes 6, 7, 8, 9 in second diagram
- But 3 is a general label for mantle in first diagram
- In second diagram, mantle includes:
- 6 → uppermost solid mantle
- 7 → asthenosphere
- 8 → upper mantle (rest)
- 9 → lower mantle
- So Mantle → 3, 6, 7, 8, 9

But wait — 3 is a single label, while others are subdivisions.

But the question says “identify each layer and sub-layer”, so:

Let’s list all the layer names and assign the correct number(s):

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🧩 Step-by-step Assignment:

| Layer Name | Corresponding Number(s) | Reason |
|-----------------------|-------------------------|--------|
| Crust | 4, 5 | Both point to the outermost layer |
| Mantle | 3, 6, 7, 8, 9 | 3 is general mantle; 6,7,8,9 are sublayers |
| Lower Mantle | 9 | Layer between upper mantle and core |
| Inner Core | 1, 11 | 1 in first diagram, 11 in second |
| Core | 2, 10, 11 | Core = Outer + Inner; 2 and 10 = Outer Core; 1 and 11 = Inner Core |
| Outer Core | 2, 10 | 2 in first diagram, 10 in second |
| Asthenosphere | 7 | Specifically labeled |
| Upper Mantle | 6, 7, 8 | Includes upper solid mantle (6), asthenosphere (7), and rest of upper mantle (8) |
| Lithosphere | 5, 6 | Crust (5) + uppermost solid mantle (6) |

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✔ Final Answer (Fill in the Circles):

Now, for each layer, write the correct number(s) in the circle.

| Layer Name | Number(s) to Write |
|------------------------|--------------------|
| Mantle | 3, 6, 7, 8, 9 |
| Lower Mantle | 9 |
| Inner Core | 1, 11 |
| Asthenosphere | 7 |
| Outer Core | 2, 10 |
| Crust | 4, 5 |
| Core | 2, 10, 11 |
| Upper Mantle | 6, 7, 8 |
| Lithosphere | 5, 6 |

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✔ Summary of Answers:

- Mantle → 3, 6, 7, 8, 9
- Lower Mantle → 9
- Inner Core → 1, 11
- Asthenosphere → 7
- Outer Core → 2, 10
- Crust → 4, 5
- Core → 2, 10, 11
- Upper Mantle → 6, 7, 8
- Lithosphere → 5, 6

> ⚠️ Note: Some layers appear multiple times (e.g., Crust appears twice — once in first diagram as 4, once as 5). So both numbers are correct.

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✔ How to Fill the Worksheet:

Go to the bottom section and write the numbers in the circles:

- Mantle: write 3, 6, 7, 8, 9
- Lower Mantle: write 9
- Inner Core: write 1, 11
- Asthenosphere: write 7
- Outer Core: write 2, 10
- Crust: write 4, 5
- Core: write 2, 10, 11
- Upper Mantle: write 6, 7, 8
- Lithosphere: write 5, 6

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🎯 Final Explanation:

This worksheet teaches the structure of the Earth using two diagrams:
- One simplified (top)
- One detailed (bottom)

By matching numbers to layers, students learn:
- The order of layers (crust → mantle → core)
- Subdivisions like asthenosphere, lithosphere, upper/lower mantle
- That lithosphere = crust + uppermost solid mantle

Correctly identifying these helps understand plate tectonics, earthquakes, and Earth’s internal dynamics.

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✔ Answer Key Summary:

| Layer Name | Numbers |
|--------------------|---------|
| Mantle | 3, 6, 7, 8, 9 |
| Lower Mantle | 9 |
| Inner Core | 1, 11 |
| Asthenosphere | 7 |
| Outer Core | 2, 10 |
| Crust | 4, 5 |
| Core | 2, 10, 11 |
| Upper Mantle | 6, 7, 8 |
| Lithosphere | 5, 6 |

You can now fill in the circles accordingly.