Carrying out classroom experiments that demonstrate Boyle's law and Gay-Lussac's law can be challenging. Even if we are able to conduct classroom experiments using pressure gauges and syringes, the results of these experiments do little to illuminate the kinetic theory of gases. However, molecular dynamics simulations that run on computers allow us to visualise the behaviour of individual particles and to link this behaviour to the bulk properties of the gas e.g., its pressure and temperature. In this article, I describe how to carry out "computer experiments" using a commercial molecular dynamics iPad app called Atoms in Motion. Using the app, I show how to obtain data from simulations that demonstrate Boyle's law and Gay-Lussac's law, and hence also the combined gas law.