*Clarification appended

A couple of weeks after Texas penalized its main testing vendor over glitches with thousands of standardized tests, another potential testing mishap is under investigation after more than 100 students in a high-performing Houston-area high school received zeros on their English essays.

Valerie Vogt, chief academic officer at Lamar Consolidated Independent School District, said she was confused this spring when about 157 students at George Ranch High School, which generally performs higher than state average on standardized tests, received zeros on their English 1 and English 2 essays. In the other four high schools in the district, just 10 or fewer students received zeros on the essays.

"There's definitely something wrong," she said.

District officials argue the problem lies with New Jersey-based Educational Testing Service, the company that administers and scores the tests, and does not reflect the performance of the high school's freshmen and sophomores. ETS and the Texas Education Agency are investigating the issue and could not say Thursday when they expected it to be resolved.

TEA spokesperson DeEtta Culbertson said Thursday that students can receive a score of zero on their essays if the page is blank or if the paper is off-topic, illegible or written in any language other than English.

Culbertson also confirmed Thursday that the agency is investigating a similar issue in Edna ISD, near Victoria.

ETS spokesperson Tom Ewing said the people who score the handwritten essays have extensive training and that the company works hard to make sure the response process is "consistent and fair for all students."

In 2016, Lewisville ISD in North Texas experienced a similar problem, with dozens of essays wrongly given a score of zero — one of many logistical errors ETS made with scoring results and online testing that year, resulting in a $5.7 million financial penalty.

Vogt said a Lamar CISD teacher with experience scoring state English tests looked at copies of essays for the students who received zeros. Those essays didn't differ much in quality from essays that received higher grades, she said.

She said most of the students affected by the potential glitch otherwise did well on the tests and the essay scores will not affect whether they can graduate. But the district might get a bump down in its state ratings, which are largely based on standardized tests, with the scores erroneously showing that students did not progress compared to last year.

"It'll be a huge impact," Vogt said.

Last month, the TEA levied a $100,000 penalty against ETS after tens of thousands of Texas students were kicked out of the testing software or encountered connection problems when taking computerized tests in April and May. The agency also announced it would throw out the scores of students who experienced those glitches and reduce their effect on state accountability ratings for schools and districts.

"We are committed to ensuring a similar event will not occur in the future and there will be a positive testing experience across the state," Ewing said in a written statement after the penalty was announced.

Disclosure: Educational Testing Service has been a financial supporter of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.

Clarification: This story has been updated to note that a Lamar CISD teacher looked at copies of essays — not the test booklets — for the students who received zeros.