It is hard like a rock.
stone
Made from trees.
wood
There's a lot of it in the desert.
sand
Long long time ago. Thousants years ago.
prehistory
in the centre / between / among
in the middle of
____ is the best material for a _____
ceramic ... pot
____ is the best material for a _____
wood ... fire
____ is the best material for a _____
stone / bone / wood ... tool
____ is the best material for a _____
wood / stone ... sculpture
