If you are at the parks near Temple of Heaven (Tiantan), you will find lots of older people spread all over the parks. You get some practising their qigongs...swordplays..all kinds of sports..and then you see some engaging in this..

You can't really see from a black & white image, but that container actually holds water..and the paintings were all done on granite floors. Pretty good way of practising calligraphy without damaging the environment I must say!