  Kinetically constrained models (KCM) are systems with trivial thermodynamics
but often complex dynamical behavior due to constraints on the accessible paths
followed by the system. Exploring these properties, the Kob-Andersen (KA) model
was introduced to study the slow dynamics of glass forming liquids and later
extended to granular materials. In this last context, we present new results on
the heterogeneous character of both in and out of equilibrium dynamics, further
stretching the granular-glass analogy.
