As a very young boy I had a girl for a neighbor about the same age. We were good friends and one day playing in the woods she asked if I would like to play doctor. I didn't know what she meant and she explained that she would examine me like the doctor did and then I would examine her. It sounded reasonable and I agreed. She had me disrobe in front of her, something that didn't bother me. At that point in my young life I had no idea about nudity, sexuality, or the difference between boys and girls; I must have been about six.
My friend, Sonya, was way ahead of me. Without any props, she proceeded to pretend to listen to my heart, looked in my eyes, ears, and throat, and then asked me to pull down my underwear which I did. She then examined my circumcised penis which she pulled and massaged as she did my testicles. It felt good and soon I had a little erection. She said this was good and normal. She also told me that I had been circumcised as a baby and that some boys (like her cousins) had skin over covering their penises. She said this was unhealthy as dirt could get underneath and said I was in good health and told me to get dressed.
Without any prompting Sonjya took off her own clothes and I was amazed to learn that she did not have a penis like I did. She lay back on her discarded shirt and opened her legs to show me her internal organs. I watched as she showed me her vagina, labia, and little clit. I mainly wanted to know how she peed and she showed me her little pee hole and went on to pee on the grass with her legs open. I learned a lot from that girl.