After watching the clip, children could have a selection of rocks and they could investigate the properties of these rocks. They could sort them by different criteria, for example, hard and soft rocks, shiny and dull rocks. Children could then start to suggest reasons why certain rocks have been chosen for particular jobs. Children could be shown different images and they could match the image to the type of rock that it has been made from. Children could attempt to use clay to make their own pencil crayon. Place the clay, in a polythene bag with powder paint (any cellulose wallpaper paste mixed with water). Squidge this around in the bag, and then roll out in 8cm lengths. Leave to dry overnight. These could be decorated with fancy paper.