Looking at rocks

By the end of this set of activities, children will be able to name and give the main characteristics of the three main rock groups, explain several uses of rocks and rock based materials, understand that soils are made from a mixture of substances including tiny particles of rocks, and explain what has been learnt from their investigations.

Introduction

Get your class together to assess what children already know about rocks. Try having a short walk around the school grounds or local area, asking children to point out objects made from rocks, such as brick walls and stone cladding, and rocky materials such as concrete paths. Ask children why they think rocks were used in the construction of these objects

Back in the classroom and working as a class, make a list of the ways in which you saw rocks being used, adding any additional ideas that come up and discussing the reasons why rocks made good materials in each instance

Types of rock

There are three main types of rock – igneous, sedimentary and metamorphic:

Igneous rock
This is formed when hot magma (molten or semi-molten rock formed below the Earth’s surface) rises up to the surface and cools and hardens – often from erupting volcanoes. Igneous rocks are made of crystals and are usually hard. ‘Igneous’ comes from the Latin word meaning ‘fiery’. Granite is an igneous rock.

Sedimentary rock
The earth’s rocky crust is being worn away all the time, and when these rock particles settle in water they eventually form into sedimentary rock. Sedimentary rocks forms in layers, may contain fossils and are usually soft. Sandstone and limestone are sedimentary rocks.