I really need help with a matter in my class. Please help me!

Well basically my teacher wants be to read out loud tomorrow. But i get nervous and the words dont come out my mouth. Kind of like a stutter. Im really worried about this and i dont know what i can do. Im in the best set, and i dont want to be moved to a lower set because the teachers may think i cant read when i can. PLEASE CAN SOMEONE GET BACK TO ME TODAY BECAUSE I START READING TOMORROW.

THANKS