What is enjected under Kat's skin before the Games? Why?

A 'tracker' is injected under the skin in Katniss's arm in order to keep track of her throughout the entire Games. This way, the gamemakers know exactly where she is, at any point during the games.

It's a tracker.

The put them on all the tributes so that they can keep track of where they are in the arena.

Basically, so they know where to go to pick up the bodies, where to aim the cameras, etc.

And of course because they "don't want to lose a tribute"-not the irony-tributes are getting "lost" (dead) every day... O.o

they put a "tracker" in her arm before she entered the arena
they did this because "they wouldn't want to lose a tribute"
hope this helps

You spelled "injected" wrong. OCD attack. Sorry XD But it's a tracker so they make sure none of the contestants get out.

A tracker, to keep a eye on her and it also tells them when her hart stops (I believe).