The boy and girl are playing on the outdoor gym.
the boy and girl are on the outdoor
Just because a boy and girl are playing on the outdoor gym doesn't mean that they are specifically on the outdoor, or "out door".
exists e1 s1 x1 x2 x3 x4.(n_gym(x4) & a_outdoor(s1) & Theme(s1,x4) & n_girl(x3) & n_boy(x2) & subset_of(x3,x1) & subset_of(x2,x1) & on(e1,x4) & Actor(e1,x1) & v_play(e1))
exists p1 x1 x2 x3 x4.(n_outdoor(x4) & n_girl(x3) & n_boy(x2) & subset_of(x3,x1) & subset_of(x2,x1) & on(x1,x4))