The National Assessment of Educational Progress (NAEP) is the largest continuing national assessment of what America's students know and how they can do in various subject areas. Assessments are conducted periodically in mathematics, reading, science, writing, the arts, civics, economics, geography, and U.S. history.
This slideshow is based on average NAEP scores in reading and mathematics for the 4th grade. The scores were taken from the 2009 NAEP, the most recent year from which results are available.
The U.S. scored 220 in reading and 239 in math, for an average score of 229.5. Keep clicking to find out how each state fared.
Idaho's fourth graders also scored an average of 231 on the reading and math portions of the 2009 National Assessment of Educational Progress, tying with Rhode Island and several other states for 15th place.
The Idaho statehouse dome in Boise, Idaho. is seen here.
Maine's fourth graders tied with Pennsylvania's for the No. 10 spot in the nation. Both states' students earned a 234 average reading and math scores on the 2009 National Assessment of Educational Progress.
Here, a boat is seen resting on shore of west branch of the Penobscot River, near Millinocket, Maine.
Massachusetts' fourth graders earned the top spot in the U.S. with their 243 average reading and math scores on the 2009 National Assessment of Educational Progress. The state scored 32.5 points higher than the lowest average scorer - Washington, D.C. - on the same tests.
Here, the Boston Common park and Boston skyline are seen.