Igneous and metamorphic rocks KS3 Activate Science | Teaching ... - Free Printable

Problem Analysis:

The worksheet focuses on igneous rocks, their formation, and characteristics. The task involves completing sentences and a table based on the provided key words and concepts.

#### Q1: Complete the sentences
The sentences are about how igneous rocks form and the differences between intrusive and extrusive igneous rocks. The key words provided are: magma, intrusive, cools, extrusive, crystallises, cooled, features.

#### Q2: Complete the table
The table requires information about two types of igneous rocks: Diorite (intrusive) and Basalt (extrusive). The columns to fill are:
- Image: Provided.
- Example: Diorite and Basalt.
- Characteristics: Physical properties of each rock.
- How is it formed?: Explanation of the formation process.

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Solution:

#### Q1: Complete the sentences
Using the key words, the completed sentences are as follows:

> Igneous rocks are formed when liquid hot rock (magma) comes up towards the surface. As it rises, it cools and crystallises, either above the surface or below the surface.
>
> We call igneous rocks which form above the surface: extrusive igneous rocks, and we call igneous rocks which form below the surface: intrusive igneous rocks. Both these rocks have different features due to the speed at which they have cooled.

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#### Q2: Complete the table

| Type of Igneous Rock | Image | Example | Characteristics | How is it formed? |
|----------------------|-------|---------|-----------------|--------------------|
| Intrusive |  | Diorite (above) | - Coarse-grained texture<br>- Large crystals visible to the naked eye<br>- Dense and hard<br>- Typically grayish in color | Forms when magma cools slowly beneath the Earth's surface. The slow cooling allows minerals to grow large crystals. |
| Extrusive |  | Basalt (above) | - Fine-grained texture<br>- Small crystals or no visible crystals<br>- Lightweight compared to intrusive rocks<br>- Often dark in color (black or dark gray) | Forms when lava cools quickly on the Earth's surface. The rapid cooling prevents mineral crystals from growing large, resulting in a fine-grained texture. |

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Explanation of the Solution:

#### Q1: Sentences Explanation
1. Magma: Liquid hot rock inside the Earth.
2. Cools and Crystallises: When magma reaches the surface or cools underground, it solidifies into rock through the process of crystallization.
3. Above/Below the Surface: Igneous rocks can form either on the surface (extrusive) or underground (intrusive).
4. Extrusive vs. Intrusive:
- Extrusive: Formed on the surface; rapid cooling results in small crystals or no visible crystals.
- Intrusive: Formed underground; slow cooling allows large crystals to form.
5. Features and Cooling: The rate of cooling determines the size of mineral crystals and the overall texture of the rock.

#### Q2: Table Explanation
1. Diorite (Intrusive):
- Characteristics: Coarse-grained texture with large crystals because it cooled slowly underground.
- Formation: Magma cools slowly beneath the Earth's surface, allowing minerals to grow large crystals.

2. Basalt (Extrusive):
- Characteristics: Fine-grained texture with small or no visible crystals because it cooled quickly on the surface.
- Formation: Lava cools rapidly on the Earth's surface, preventing the growth of large crystals.

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Final Answer:

#### Q1:
- Igneous rocks are formed when liquid hot rock (magma) comes up towards the surface. As it rises, it cools and crystallises, either above the surface or below the surface.
- We call igneous rocks which form above the surface: extrusive igneous rocks, and we call igneous rocks which form below the surface: intrusive igneous rocks. Both these rocks have different features due to the speed at which they have cooled.

#### Q2:
| Type of Igneous Rock | Image | Example | Characteristics | How is it formed? |
|----------------------|-------|---------|-----------------|--------------------|
| Intrusive |  | Diorite (above) | - Coarse-grained texture<br>- Large crystals visible to the naked eye<br>- Dense and hard<br>- Typically grayish in color | Forms when magma cools slowly beneath the Earth's surface. The slow cooling allows minerals to grow large crystals. |
| Extrusive |  | Basalt (above) | - Fine-grained texture<br>- Small crystals or no visible crystals<br>- Lightweight compared to intrusive rocks<br>- Often dark in color (black or dark gray) | Forms when lava cools quickly on the Earth's surface. The rapid cooling prevents mineral crystals from growing large, resulting in a fine-grained texture. |

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