## When they did not find him ##

"When Mary and Joseph did not find Jesus"

## It came about that ##

This phrase is used here to mark an important event in the story. If your language has a way for doing this, you could consider using it here.

## in the temple ##

This could be translated as "in the temple courtyard" or "at the temple."

## in the middle of ##

This does not mean the exact center. Rather, it means "among" or "together with" or "in the midst of" (UDB).

## the teachers ##

"the religious teachers" or "those who taught people about God"

## at his understanding ##

This could be translated as "at how much he understood" or "that he understood so much about God."

## his answers ##

This could also be translated as "at how well he answered them" or "that he answered their questions so well."