Found in the ground - grouping materials

This week's new Earthlearningidea is 'Found in the ground: sorted!'  This activity is an introduction to classification using things 'found in the ground'.
Pupils are provided with a box of assorted items, most of which come straight from the ground, but also including one or two manufactured objects. A typical list is given under 'Resources' in the activity. The pupils are asked to sort the items into groups,
using their own criteria, and without any prior briefing regarding the usual names for materials of geological origin. They may set up as many groups as they like, so long as they can justify why they have placed items in each group. Tell them that, when they have finished, you will want them to justify their reasons for their groupings.
This is one of many activities in our Earth Materials category.