If your son is ten years or older, he is likely noticing changes happening in his body. Puberty is the time when testosterone begins to have obvious effects in his skin, muscles, and of course, his reproductive structures.
Your 9-10 year-old son is likely becoming curious about his boy body. He has entered puberty and has begun to notice changes.
It might be interesting for your young son to learn that his testicles are sensitive to temperature. The testicles are located inside a sack of skin called the scrotum. The scrotum is very thin. It doesn’t provide good insulation from temperature changes that might affect the testicles. This anatomy illustration is from by book, “I’m a Boy, Special Me.”
Unless a boy grows up in a family where there are sisters, it might be difficult for him to learn very much about the changes that happen to girls during puberty. By the time boys are about 13 years old, they likely have many questions that might go unanswered. This is the time to begin teaching him basic information about girl anatomy and function.
It is always interesting to have talks with small groups of girls who have recently started having regular periods. They cautiously make their way into a questioning time about how boys are different. They almost sound like they feel guilty asking me about this.