How can i train my pet rats to come when i call there name?

Never feed your rats chocolate chips. The best way to get them used to their names is to say it in the same way everytime you greet them, come in the room, pick them up, and give them treats (veggies, natural balance dog food, seeds). Then after a while, put them to the test by placing them into an open space and call their name the same way you have done it before. Then you will know if they've learned it. If they come, use food and petting as positive reinforcement.