The term 'Grade Booster' refers to activities or strategies that can help improve a student's grade. The two crossword solutions for this term are 'PLUS' (4 letters) and 'Extracredit' (11 letters). PLUS is an activity that can be used to increase a student's grade, such as taking an extra course or doing additional research. Extracredit is a strategy that can be used to boost a student's grade, such as completing extra assignments or participating in extra-curricular activities. Both of these activities and strategies can be used to help students improve their grades and achieve their academic goals.