Mathematics seems to have a special role in models that attempt to describe reality: for example the models of physics are implemented using mathematics; a big part of the chemistry and life sciences use mathematics to describe the phenomena; a big part of economics is applied mathematics and mathematical models are used in sociology, psychology, genetics and many other disciplines. An interesting question that cognitive science can try to ask is: why? Why seems to be so strong link between natural and human phenomena and mathematics? Why has become natural for us to use concepts and mathematical techniques to create models of phenomena that we study? A possible answer might be found in the eventual convergence of some aspects of mathematics and the development of particular cognitive skills. In this paper we try to assess whether a particular aspect of mathematics, the concept of closure as to an operation, is in some way related to the ability to perform tasks of (sequential) ordering.