Rocks on the surface of the Earth can be worn away by the weather into interesting shapes. Rocks can be soft or hard. Soft rock is more likely to be worn away by the weather over long periods of time. Some rock shapes are formed over millions of years.

This clip is from:
Science Clips, Rocks and Soils
First broadcast:
9 October 2007

This clip could be used as an introduction to the different properties of rocks when studying materials. Pupils could be given a variety of rocks to examine closely. Several questions could be asked: "Which is the softest rock? Which is the hardest rock? Which is the heaviest? Which is the lightest? Which is the most porous? Which rock do you think would weather the most?". Children could choose a question to investigate, carrying out a detailed experiment, identifying variables, making predictions and drawing conclusions from their findings eg "Which rock is the most porous?" (Use the same size rock and the same amount of water, measure how much water passes through the rock within a certain amount of time).