Less than one-in-five eighth graders have a proficient grasp of United States history, and less than a quarter have a proficient grasp of civics, according to new government data released Wednesday.

Overall, the average scores for eighth-graders are not significantly better or worse than they were in 2010, the last time the National Assessment of Educational Progress examined eighth-graders' knowledge of geography, civics, and U.S. history.

One question from the test gave a partially-completed table with the three branches of government and asked students to identify each branches' power and one way other branches limit that power.

Only 7 percent of students got complete credit for the question, with another 10 percent giving acceptable answers in three of the four empty boxes.

Another multiple-choice question asked about the landmark 1803 Supreme Court case, Marbury v. Madison. Despite being given four choices, only 41 percent of students correctly responded that the court's decision established its own power to decide whether a federal law is constitutional.

One percent of students have an advanced knowledge of U.S. history, while two percent are considered advanced in civics and three percent in geography.

Compared to the first assessment in 1994, eighth-graders average test scores are slightly higher in history, and slightly improved from the first civics assessment in 1998.

Students also answered survey question about their classroom activities. When studying civics, less than half of students discussed current events in class, fewer than in 2010. Fewer students also read textbooks in class or took part in role-playing activities, while more watched videos and used computers at school. Just 7 percent of students took part in a mock trial or other type of role-playing activity

When studying history, less than two out of three students read textbook material in class. The share of students who watched videos, used computers or listened to information online during class rose. The share who read essays, letters or diaries written by historical people rose to 22 percent from 17 percent.

The average history score was 280 points out of 500 in private schools, compared to 266 in public schools. In civics, private school students averaged 168 points out of 300, compared to 152 for their public school counterparts.

Students of Asian descent continued to outscore white students in U.S. history, increasing their small lead from one point to two since 2010. Asian students outscored white students in civics for the first time, although only by one point.

The stalling academic results are a source of concern for those who think a thorough knowledge of U.S. history, geography, and civics is necessary for a thriving democracy.

"If the next generation doesn't understand the causes and the purpose of our American Revolution, the reasons for the separation of powers in our government or the role of the states in our federal system, that generation isn't likely to notice when its liberties slowly slip away and will not be equipped to hold elected officials accountable," Roger Beckett, the Executive Director of the Ashbrook Center, said of the assessment.

"There is still a lot of work to be done, and parents, teachers, education leaders and public officials need to rededicate themselves to the important task of teaching American students about the history of our country and its unique form of representative government."

The 2014 National Assessment of Educational Progress was given to more than 29,000 eighth-graders across the country. Each student participated in one of the three subjects: U.S. history, geography and civics.