Expositor's Bible Commentary Commentary Luke 2:43

"and when they had fulfilled the days, as they were returning, the boy Jesus tarried behind in Jerusalem; and his parents knew it not;" — Luke 2:43 (ASV)

At this intermediate age, Jesus might have been either with the women and children or with the men and older boys, the way the families were probably grouped. Each parent might have supposed he was with the other. After a day of travel Mary and Joseph missed Jesus; another day would have been required for the trip back, and on the next day (“after three days,” v.46) the successful search was made.

The questions Jesus put to the teachers were probably not merely boyish inquiries but the kind of probing questions used in ancient academies and similar discussions. He also gave answers, some of which amazed the teachers.