I was wondering if any one can lead a prayer?. because we pray at school and people tell us why dont one of us lead a prayer?

and what things invalidates fasting?

1462. The Imam of the congregational prayers should be:
Adult (Baligh) Sane Ithna 'Ashari Shi'ah 'Adil Of legitimate birth Being able to offer the prayers correctly
Furthermore, if the follower is a male, the Imam also should be a male. To follow a boy of ten years of age is a matter of Ishkal