When my kids were little, and we were in the truck by ourselves (that meant my wife was at home, tending the home fires), I would tell them I could drive with my eyes closed. Since they were seated next to me, and could not see both my eyes, I simply closed my right eye. they always wondered how I could drive that way. I'm not sure when they figured it out. I only did it on our road, where there was little or no traffic, without any cross streets.