http://www.bbc.co.uk/schools/scienceclips/ages/8_9/solid_liquids.shtml
http://www.bbc.co.uk/bitesize/ks2/science/materials/
http://www.bbc.co.uk/schools/scienceclips/ages/9_10/changing_state.shtml
http://www.bbc.co.uk/schools/scienceclips/ages/7_8/characteristics_materials.shtml
http://www.bbc.co.uk/schools/scienceclips/ages/9_10/science_9_10.shtml