My understanding is that for more than either 5 or 6 hour work period you must give 2 x 15 minutes paid breaks and time for a 30 minute lunch that does not have to be paid. I think for 4 hours you must provide a single 15 minute break but don't hold me to it.
This is why many employees work an 8.5 hour day, the lunch doesn't count.
You of course, do have the option to pay them, but it is not mandatory.
