instead of
conceding and simply saying "I'm forgeted" while doing nothing about the problem, take action
talk to your teacher about it after school
use the resource rooms if they're provided
take notes on the classroom material, then study them for the test
make flashcards or something to help learn vocabulary
see if you can benefit from a homework help program if most of your grades are from homework
speaking of, make sure you complete the assignments given to you in class in a timely fashion