Eighth-graders across the country slightly improved their basic science skills over the past two years, but about seven out of 10 still were not considered “proficient” on a national test, and experts worried about what the results said about American competitiveness.

Two-thirds of eighth-grade students performed at or above a "basic" achievement level on a national science assessment test, suggesting at least a "partial mastery of the knowledge and skills needed for proficient work," according to The National Assessment of Educational Progress.

"We didn't know what to expect with a test like this," said Stephaan Harris, spokesman for the National Assessment Governing Board, the independent board that sets NAEP policy. "Overall, there was improvement and gains."

The average eighth-grade score increased two points, from 150 in 2009 to 152 in 2011, according to the NAEP. The test is scored on a 300-point scale. The assessment was released Thursday.

 Among assessment findings:

• 32 percent of students performed at or above "proficient" and 2 percent performed at an "advanced" level, Harris said. The NAEP defines "proficient" as showing "solid academic performance.”
• Black and Hispanic students showed more improvement than white students, narrowing but not eliminating the achievement gap, Harris said. Hispanic students scored a five-point gain, while black students scored three points higher compared to 2009 results.  
• The gender gap remained unchanged, with male students scoring five points higher on average than female students.

Read the NAEP's complete Science 2011 findings

"The gains are encouraging, but the racial and gender gaps show a cause for concern," David Driscoll, chairman of the National Assessment Governing Board, said in a statement. "In order to compete in globally competitive and expanding fields like technology and medicine, we must make sure we give our students the tools necessary to excel in an important subject area."

Gerry Wheeler, interim head of the National Science Teachers Association, described the gains as "minuscule," according to The Associated Press.

"When you consider the importance of being scientifically literate in today's global economy, these scores are simply unacceptable," the AP quoted Wheeler as saying Thursday.

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More than 120,000 eighth-graders from 7,300 schools nationwide participated in the exam last year. According to the assessment analysis, of the 47 states that participated, 16 showed a small increase in their science scores over 2009's results. Most states stayed flat, the study showed.

The assessment also found that students who performed daily hands-on science activities scored higher on average than students who performed them less frequently. The 2011 science assessment test measured knowledge and abilities in physical science, life science, and earth and space sciences.

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A Missouri mother says her 6-year-old daughter was humiliated after she was denied a bathroom break in her kindergarten class and was forced to sit in her diarrhea during a test session at school.

"They didn't even bother trying to clean her up or anything. She still had poop, diarrhea poop, coming out the back, up her front, down her legs," said the mother, Lisa Skidmore of Washburn, Mo., told KY3-TV on Tuesday.

KY3-TV, an NBC News affiliate in Springfield, Mo., was first to report the story.

The incident happened at Southwest Elementary School in Washburn, Mo., where children were participating in the Missouri Assessment Program tests; the state standardized testing required by law. 

While tests are not administered until the third grade, the child's kindergarten teacher was sticking to MAP testing guidelines in efforts to simulate the stringent rules to prepare students for what's to come, School District Superintendent Bob Walker told KY3-TV on Tuesday.

"Bottom line, we regret what happened," Walker told KY3-TV.

Walker, who was contacted by msnbc.com on Thursday, said he met with the child’s parents on Wednesday.  

“From our view point, this is a confidential matter and in regards to the media, we want it to remain that way,” Walker told msnbc.com.

In earlier interviews, Walker said he instructed teachers to be more sensitive to situations that might arise during tests.

"I don't want this to happen to any other kid. That's the point of this: I don't want this ever happening,” Walker said, according to KY3-TV.

The child’s mother said she has asked school officials for an explanation and a policy change.

"They told me that the teacher had asked her to go to the restroom before testing time," Skidmore said, according to KY3-TV.

Skidmore says her daughter was forced to sit in the class for the remainder of test time, about 15 minutes, then she was called after the test, and it was a 20-minute drive to the school, according to KY3-TV.

No one helped to clean up her child, she said. A teacher, however, did give the child a trash bag to wrap around herself, Skidmore said.

"You don't even treat a dog that way!" Skidmore told KY3-TV.

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