This Kapow pupil video is part of the Kapow Science scheme of work. Rocks can be grouped into three main categories depending on how they are formed: sedimentary, metamorphic, and igneous. Sedimentary rocks form when weather, such as wind, rain, or frost, breaks pieces off other rocks. These small pieces are carried away by water to rivers and the sea. As the water slows, they sink to the seabed, forming layers of sediment. Over millions of years, the weight of the top layers squashes the ones underneath, sticking them together to make sedimentary rock, like sandstone, limestone, mudstone, and coal. Sometimes you can see the layers clearly.

Igneous rocks form when rock becomes so hot it melts into liquid. Underground, it’s called magma, but above ground, it’s lava. When lava cools, it hardens into igneous rock, such as granite, obsidian, pumice, or basalt. Metamorphic rocks form when sedimentary or igneous rocks are pushed deep underground near magma. Heat and pressure change the rock into something new, like slate, marble, or schist. Over time, all three types of rock can break down into sediment and start the cycle again, showing that the rock cycle is never-ending.

The video is designed to be shown to pupils as part of Science, key stage 2, Year 3, Materials: Rocks and soil Lesson 1: Rocks: Appearance