## his parents ##

"Jesus' parents"

## they went up ##

Jerusalem was on a hill, so people had to go up to it.

## after they had stayed the full number of days for the feast ##

"when all the days of celebrating the feast were over" or "after celebrating the feast for the required number of days"

## they assumed ##

"they thought"

## the traveled a day's journey ##

"they travelled one day" or "they went as far as people walk in one day"