Where were the kids traind to be Spartans at?

Answer 1

The original batch of Spartans were selected as children from their home worlds among the various human colonized systems. Most of their training was done aboard a UNSC vessel, where they were subjected to vigorous training many times more difficult than marine training today. Their bones were covered with a highly hardened metal to reduce and all but eliminate breaking problems. They were fed growth hormones and different brews of chemicals to increase reaction time and resistance to shock.

Moomaster