We are going throught a huge heat wave in the midwest so I went to one of the local splash pads with a friend's kids and got a chance to try some things for this weeks invisible challenge. The first thing that was present there and noone could see was the heat, although it was  pretty obvious as soon as the kids were able to get some relief in the water.  On the edges of the playgrounds there was also evidence of the little ones that were around.
Finally, what is the thing that i invisibl in almost every photograph? well, the photographer, and in this shot I was able to capture myself taking the picture in the  reflection of one of the kids eyes.