A still life is the most patient subject there is: it does not move, it does not mind being looked at, and it will wait while you work out what colour a shadow actually is.
The tables are set with objects to choose from — glass, ceramic, fruit, fabric, a few things that catch the light oddly. You arrange your own group, which is already half the painting.
The guidance is on seeing rather than technique: how much darker a shadow really is, why white objects are almost never white, how to keep an edge soft. It is a calm evening, and the paintings that come out of it tend to surprise people.