Three children are on the floor playing with building blocks.
Three children play with legos.
The children could be playing with building blocks that are not legos.
exists p1 x1 x2 x3.(n_playing(x2) & of(x2,x3) & n_floor(x3) & exists x4 x5.(on(x1,x2) & with(x2,x4) & n_block(x4) & of(x4,x5) & n_building(x5)) & n_child(x1) & card_eq_3(x1))
exists e1 x1 x2.(with(e1,x2) & n_lego(x2) & Actor(e1,x1) & v_play(e1) & n_child(x1) & card_eq_3(x1))