The strength of paper is important because we use paper for many different things. For example, you would not use the same strength of paper for blowing your nose and carrying the shopping! Paper is made from plant fibres, matted together to form a sheet. Paper used to be made from rags and was expensive. Now it is made from wood, especially coniferous trees like pine, spruce and fir, and is much cheaper. A very important property of paper is its tearing-strength, i.e. how hard it is to tear. Some kinds of paper tear more easily than others. There are various ways of carrying out scientific tests to see which paper is the strongest, weakest,