Uhh... while a seed isn't sprouted it doesn't need light, nor have the ability to absorb it.

The paper towel method is tried and true. I had seeds spitting out a taproot in 2 days. Some beans take longer due to the strain, age, bean charaterisitcs.

Put all the beans in a glass of water, ones that sink will work. Ones that float probably wont (although i germed a few for kicks and they sprouted, so i handed them off to a friend).

Some beans just take a heckuva long time. I've heard of legit beans taking up to three weeks or so. Id argue that healthy beans sprout faster, but it could be more strain related then individual bean related.