Four children learn how to work on bicycles.
Children are being taught a lesson.
You can not infer there was a lesson.
exists e1 p1 s1 x1.(a_how(s1) & Manner(e1,s1) & Topic(e1,p1) & Actor(e1,x1) & v_learn(e1) & exists e2 x2.(on(e2,x2) & n_bicycle(x2) & Actor(e2,x1) & v_work(e2)) & n_child(x1) & card_eq_4(x1))
exists e1 x1 x2.(Recipient(e1,x2) & Theme(e1,x1) & v_teach(e1) & n_lesson(x2) & n_child(x1))