Non-ferrous metals and alloys; thin sheet metal and wire
Non-ferrous metals include aluminium, copper, zinc, tin, lead, nickel, cobalt and others; they are mostly used as alloys because some properties beat cast iron and steel. Aluminium is silvery, light (about three times lighter than steel), plastic, corrosion-resistant and conducts electricity and heat well; it is not found free in nature but in compounds. Aluminium alloys silumin and duralumin are used in aircraft building and engineering. Copper is reddish, ductile and conducts electricity and heat very well, so electric wires are made of it. Copper alloys: bronze (copper + tin and others) is strong and wear-resistant, and art objects are cast from it; brass (copper + zinc) is yellow, hard and suits parts working in damp places. Pure tin is a soft silvery metal used as a protective coating for steel sheet. Zinc is moderately hard and forms a protective oxide film. Lead is soft and bluish-grey but poisonous: pupils do not work with it, and hands are washed with soap after touching it. When studying samples never put them in the mouth, breathe in their dust or filings, or hold sharp edges with bare hands.
Sample table: 5–6 metal samples prepared by the teacher (edges smoothed, no lead) are examined; pupils record colour, weight and shine and guess the metal. Hands are washed after handling the samples.