An educational lattice model is proposed for the investigation of the influence of the density and indirectly of the pressure on the chemical equilibrium of the ideal gas phase reaction A [equilibrium] 2B. The model can be introduced by a board game simulating a stochastic process. This game can also be used to set up a corresponding computer algorithm. The solutions of this model by stochastic simulations are compared to the analytical solutions for the equilibrium state and to the numerical solution of the corresponding differential equation. It is the aim of this approach to introduce examples of the scientific method of simulation at an early stage of chemical education such as secondary education using a simple model. It furthermore allows students to deepen their understanding of chemical equilibria and the Le Châtelier density as well as pressure effect on the equilibrium at that level.