When you put the tube back in, put the logo of the tire where the stem hole is. This way, you have a reference point for the tube and the tire. In the future, when you get another flat, you will know where to look in the tire for an object by where the hole is in the tube. Or, if you know where the object is in the tire, you know where to look on the tube for the puncture.

This came in handy this last week for me. I had a thorn in the tire but could not find it and I did not feel anything on the inside of the tire. I found the hole in the tube and patched it then went back to the tire and looked in the area where the tube had been punctured. The thorn was slight and not very long. I had to push down on the tire to feel it. Had that same problem with a sliver of glass once too.