That really depends. In Eisenach it is said, he didn't show up positively. It's handed down, that he missed lessons often. Why? Experts don't have a common opinion. Some guess, there were reasons, which students still today tell to skip one lesson or an other. Others think, that it was just necessary for a large family in hard times like for the Bachs back then, that the musician Johann Ambrosius Bach needed the support of his son Johann Sebastian to make music on different occasions.
99 Music Calendars, Composers Calendars and Bach Calendars