Student or Learner
For the above sentences, which one is the proper /right way to tell to the kids?
- Focus on your own works.
- Concentrate on your own works.
It is more usual, especially for a teacher, to call them children, rather than kids. The word 'kids' is quite dismissive and would be used for example if someone else's were making an awful noise, when you might say to a friend "Bloody kids!"
Of your two options, I would use the second: Concentrate on your own work.
(Work is your job, your task or your effort. Works are in the road (roadworks) or on a site (building works) or even the collected works of Shakespeare!)
'Focus', in this sense, is a word used more with adults.