First let me say that I am not advocating the poster do something illegal, but presenting a different perspective. While what you say is true, @yyy, many schools put real students in mock lessons. It’s common practice. Even my uni did it when I applied for a job there. So this rule is rarely enforced by buxibans and schools. If you got busted during your one-time mock lesson that’d be incredibly bad luck and timing. The poster could explain the danger of this situation and hope they understand. On the other hand, if you decline to do one based on that principle, the school might shrug and say “okay, next applicant then.”