How can the state of the gonads (active or passive from a physiological point of view)

How can the state of the gonads (active or passive from a physiological point of view) be assessed in pupils of 10-15 years old in appearance?

This is noticeable in the degree of development of secondary sexual characteristics (breast growth in girls, facial hair in boys, the manifestation of physique peculiarities inherent in men and women, the appearance of hair on the body, including under the armpits). In addition, a change in the timbre of the voice in boys can be noted (although this is not a visual sign). All this indicates the activity of the gonads, while physiological maturation can, unfortunately, seriously lag behind the social and psychological).