turn + a certain word

When Tom’s aunt sent him off to school, he sometimes would go part of the way and then turn inside/outside/aside/side and go to the river to swim.

I have two questions:

  1. What does the underlined phrase denote?
  2. Which one is correct: turn inside/outside etc…?

Many thanks…

He would go some of the distance between home and school, but not go all the way to school.

He would turn aside (turn away from the predetermined path).

In other words, his aunt thought he was going to school, but Tom Brown was playing truant.