A female teacher with three students at her side, work on the chalkboard in front of a class of students.
The teacher is singing to a potato.
A teacher is either working at the chalkboard or is singing to a potato, but not both. Nothing about the first sentence implies that singing is involved.
exists s1 x1 x2 x3 x4 x5 x6 x7 x8.(n_chalkboard(x5) & a_topic(x1) & with(x1,x2) & rel(x2,x4) & on(x4,x5) & in(x5,x6) & of(x6,x7) & of(x7,x8) & n_student(x8) & n_class(x7) & n_front(x6) & n_work(x4) & at(x2,x3) & n_side(x3) & of(x3,x1) & n_female(x1) & n_student(x2) & card_eq_3(x2) & n_teacher(x1) & a_female(s1) & Theme(s1,x1))
exists e1 x1 x2.(n_teacher(x1) & to(e1,x2) & n_potato(x2) & Actor(e1,x1) & v_sing(e1))