Restrict certain JIRA developers to a single project?

It depends which groups have the Developer and User project roles. By default these are jira-developers and jira-users. I would create a new project TRAINING and grant the Developers and Users roles to the trainee user ids explicitly.

Now they can play in that project.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.