Jerry, how many chickens do you have? Also, if you have several different breeds it will be easier to tell by the color egg they lay.
Do you have seperate pens in your coop such as a brooding pen or breeding pen that you can use to seperate the hens just to figure out who is laying?
Another way is if you can just rig something up to seperate them, put up plywood or whatever and stick a nest box in with the hens you want to test, you can use a wooden box, milkcrate or whatever you have handy as a temporary nestbox.
If you have the time you can even take turns crating the hens overnight so you see if they are laying, although it may cause stress on them and they may not lay that same day.
Its hard to tell who is laying sometimes.
Sometimes hens will hangout in the nestboxes without laying, I have one that has never laid an egg in her life yet she likes to go and sit in the box.
She will spend an hour in there and then get up and leave and there is still no egg so its tough to tell who is laying sometimes. You can't assume that you see them in the boxes that they are laying.
I am not entirely sure who is laying right now and who isn't.
Its easy when they lay blue and green eggs, or even those cream colored ones because they are easy to match up to the right hen, but those brown eggs, forget it.