For years, American students have consistently ranked poorly compared to most developed nations. And according to a recently released study, the U.S. education system remains mediocre, receiving a C− grade, for the third year in a row.

Education news and research publication Education Week released its 18th annual survey of the status of education in all 50 states.

The K-12 Achievement Index is one indicator in Education Week’s “Quality Counts” report that measures key education outcomes and provides ranks and grades for each state based on their commitment to improve educational policies and practices. This year, Massachusetts received the highest score, a B, while Mississippi got an F. 24/7 Wall St. reviewed the states with the best and worst scores for K-12 achievement.

These are the states with the best and worst schools.

The Worst Schools
10. Oklahoma
9. Michigan
8. South Dakota
6. Alaska
5. Alabama
4. West Virginia
3. New Mexico
2. Louisiana
1. Mississippi

The best Schools
10. Colorado
9. Washington
8. Pennsylvania
7. Florida
6. Minnesota
5. Vermont
4. New Hampshire
3. New Jersey
2. Maryland
1. Massachusetts