I will present the results of recent high resolution numerical
simulations of dwarf spheroidal galaxies in which both the dynamical and
the chemical evolution of the systems are followed. We used the
unprecedented large database offered by our ESO Large Program DART to
constrain our models: samples of hundreds of stars with precise
chemical abundances from UVES high resolution spectroscopy. I will show
up to which extent the Local Group dwarf dSph galaxies can be formed
within a common framework despite today apparent different age and
abundance properties and describe the main driving parameters leading to
formation of these small galactic systems. New constaints on a number of
critical parameters such as the supernova feedback, and the IMF will be
discussed.