"Sexual activity" refers to any physical or intimate behavior that is related to sex, such as kissing, touching, or any other activities involving a person's sexual organs. Full definition
Half of the respondents reported engaging in sexual activity of some kind, with or without a partner, in the past month. (livescience.com)
They found that every additional hour of sleep brought with it a 14 percent rise in the likelihood of having some kind of sexual activity with her partner. (inc.com)
So I think it's important to talk to young girls that may be are engaging in sexual activity with other girls. (kidsinthehouse.com)