Occasionally, I head out to volunteer to teach robotics programming at an all-girls school in my area. For context, I'm male and age 20, and the students are adolescent females in 7th and 8th grade (13-15 year olds).
When I head out to teach, most of the students there treat me professionally, with a teacher-student relationship. I usually act "fun" with the students, as if I were another kid with similar interests. However, a few attempt to flirt with me, asking me about my relationship status or complimenting me on my appearance. (The flirting is completely verbal and not physical in any way.)
I understand where they're coming from; they're adolescent teenagers who don't normally see younger males (though the school does have male teachers and staff, but they're much older). For my part, I don't have any "embellishments" or any specific features that would render me "attractive" in my society, but one student has commented that I look "younger" than my age.
When one of these students starts to flirt with me, how can I make it clear that this isn't the right time or place to make such comments or questions and that they should be treating me professionally? The director of the program has told us to lie about our relationship status (i.e. to say "I have a girlfriend") in response to such comments, but I'd prefer not to lie to accomplish my purpose.
Note: Not a duplicate of How to handle students in a classroom who might have feelings for you?. First of all, the person in question is not only much older, but also the consistent instructor of the class; I, on the other hand, am just a volunteer who goes there on an infrequent basis. Second, the "feelings" in question there are genuine romantic feelings, not just casual flirting. Third, the "students" in question there are grown adults at about my age; the answer may be different for adolescent children.
Additionally, the top answer there isn't really a way I wish to handle this situation. I can't "stop flirting with my students" because I am not. Also, I don't wish to say things like "that's not relevant to this discussion" because I'm a volunteer, not a teacher, and the attitude I wish to show to my students is that of a "fun" person who's also knowledgeable; saying direct things like "that's too personal" is too direct for my purpose. The other answer there completely contradicts this as well.