According to the 2009 PISA, China is the highest performing education system. Other particularly high performing education systems are those of Canada, Finland, Hong Kong, Japan, Singapore and South Korea.
The question you are asking is education, not overall "average grade". Most countries kick out the mentally disabled just to get a better "average". If you want a good education, the best country would be the United States.
I believe one person summed it up quite nicely. It all depends on what aspect of education you refer to. However, you can find the statistics by searching the top 10 countries for education. Apparently, Scasey789 doesn't know West Virginia is a state and not a country and this country J031 is actually the United States "of" America. The America's are continents (North, Central & South) to say America, I'd say which one? I'm aware the U.S. is frequently referred to as America but in reality it's the United States of America.