a beach ball is a kind of container & if a flexible container is pushed on then that container will change shape & a beach ball is flexible ->  if a beach ball is pushed on, then the shape of the beach ball will change  if a beach ball is pushed on, then the shape of the beach ball will change & the beach ball is pushed on the middle ->  the shape of the beach ball will change  matter in the gas phase has variable shape & air is a kind of matter & air is in gas phase ->  air is a matter that has variable shape  air is a matter that has variable shape & matter with variable volume and shape takes the shape and size of its entire container ->  air takes the shape of its container  air takes the shape of its container & a beach ball is a kind of container & the beach ball is filled with air ->  air takes the shape of the beach ball  the shape of the beach ball will change & air takes the shape of the beach ball -> the shape of the air in the beach ball will change with the shape of the beach ball