A man teaches a classroom of children.
A man is writing on a chalkboard.
A man teaching a classroom of children doesn't have to be writing on a chalkboard.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_teach(e1) & of(x2,x3) & n_child(x3) & n_classroom(x2) & n_man(x1))
exists e1 x1 x2.(on(e1,x2) & n_chalkboard(x2) & Actor(e1,x1) & v_write(e1) & n_man(x1))