A lady is writing on a board.
The lady is teaching her class with a demonstration on the board.
Just because a lady is writing on a board doesn't mean she is teaching her class with a demonstration.
exists e1 x1 x2.(on(e1,x2) & n_board(x2) & Actor(e1,x1) & v_write(e1) & n_lady(x1))
exists e1 x1 x2 x3 x4.(n_board(x4) & n_class(x2) & of(x2,x1) & n_female(x1) & n_lady(x1) & Theme(e1,x2) & Actor(e1,x1) & v_teach(e1) & with(x2,x3) & on(x3,x4) & n_demonstration(x3))