When we were eight we were given an impromptu lesson on it and I asked where do girls wee from. My teacher told me they wee from the same place as boys so I believed girls wee from their penis.
If you're worried about being pressured into sex, just "keep things vertical" because it's not possible to have sex without lying down.
Edit: since I wasn't clear on this, the teacher said all of that. The first part is good advice.