American students can successfully complete science experiments at school, but can't explain their results.

A new report out of the National Assessment of Educational Progress indicates that American students -- namely, fourth-, eighth- and 12th-graders -- can identify the correct answers to scientific tasks, but struggle to use evidence from their experiments to explain their results.

Katherine Carroll, an 11th- and 12th-grade chemistry teacher in Waterboro, Maine, told the Associated Press that even her top students struggle to explain their conclusions in lab reports, as they find themselves more comfortable answering questions with just one right answer.

"Teachers have moved towards teaching more knowledge, as opposed to the understanding behind that knowledge," Carroll told AP.

The findings draw on national debate surrounding standardized testing and widespread protests against a growing emphasis on examinations that have led to a teaching-to-the-test phenomenon.

According to a summary of the findings, students in the aforementioned grades were challenged by parts of investigations that contained more variables to manipulate or involved strategic decision-making to collect appropriate data.

Just over one-fourth of high school seniors could correctly choose and explain answers about heating and cooling. While twice that proportion -- 54 percent -- of eighth grade students could support correct responses, only 15 percent of fourth graders could explain correct experiment results with evidence.

In one task, 12th-grade students were asked to investigate the best site for building a new town based on the quality of a given water supply. While 75 percent of seniors were able to correctly perform the experiment, only 11 percent could provide a final recommendation with supporting evidence from the data.

It’s tragic that our students are only grasping the basics and not doing the higher-level analysis and providing written explanations needed to succeed in higher education and compete in a global economy,” NAEP chairman David Driscoll said in a statement, according to CNN.

The testing involved over 2,000 students from public and private schools during the 2009 school year. This marked the first time the National Assessment of Educational Progress -- known as the Nation’s Report Card -- measured how students performed on hands-on and interactive computer tasks, as opposed to more traditional “paper and pencil” tests.

The report found that female students in all three grades out-performed their male counterparts on the hands-on tasks, but males scored higher on the paper-and-pencil science assessment.

As part of the assessment, students and teachers also answered survey questions about science learning and instruction. Approximately 92 percent of fourth-graders and 98 percent of eighth-graders had teachers who reported doing hands-on activities with students at least monthly, while only 51 percent of seniors reported designing a science experiment at least once every few weeks.

According to a report released in May, only a third of eighth-graders who took a national science exam administered by the National Assessment of Educational Progress in 2011 were proficient. Gerry Wheeler, interim director of the National Science Teachers Association, lamented the statistic as “simply unacceptable.”

Also on HuffPost: