4:22 p.m. May 24 | Updated Last month’s mandated standardized tests drew widespread criticism from many parents, who complained the tests were now dominating the curriculum and that too much weight is being put on the results to evaluate their children and teachers.

Yet, despite the complaints over “high-stakes testing,” only a small group of parents decided to opt their children out of them, as many parents said they worried about the ramifications to their child and their schools if they did so.

But as city students have begun a new round of standardized tests — this time so-called “field tests,” which are experimental tests that the state-contracted test-maker, Pearson, is using to try out questions on city students for future use — more parents are talking about opting out. And test resistance appears to becoming more widespread, with substantial numbers of parents at several city schools deciding their children would not participate.

Resistance also appears to be growing more organized. Groups like Change the Stakes are helping to spread information about opt-out procedures and have created a spreadsheet to help parents navigate the field testing landscape.

ParentVoicesNY has created a boycott form letter that parents can download, sign and then submit to their school. The group also has direct connections with more than 20 schools, according to Kevin Jacobs, a public school teacher who is one of its active members.

City officials said they will not have the final figures on how many parents chose to have their children opt out last month of the federally mandated standardized math and English tests for third through eighth graders. Results from these tests play a major role in grade promotion, middle and high school applications, and placement into gifted and talented programs. Test scores are also used in teacher and school evaluations.

And no opt-out figures are available for the field tests, which focus on science, math or reading, depending on the school and the grade level. The science tests were taken last week, while the math and reading tests are slated for the first week of June.

An official at the city’s Department of Education said that unlike with last month’s standardized tests, the city does not monitor and analyze data from the field tests. The field tests are handled directly by Pearson, the official said, and the city’s approach to them is hands-off.

The field tests are being given to help Pearson, the company who received a $32 million contract to design New York’s state tests, align its questions with the new Common Core learning standards. But it is doing so in an increasingly critical atmosphere, after multiple problems with last month’s tests, including errors in the multiple choice answers and complaints about a farcical passage related to a race between a pineapple and a hare.

About 488,000 students will be involved in this year’s field tests, a spokesman for the New York State Education Department said. But last month’s standardized tests also had embedded field questions that will be used by Pearson purely for research purposes. As a result, the tests were 30 percent longer, another source of frustration for children and their parents.

So why the need for the standalone field tests?

The state Education Department spokesman said the validity and reliability of the state exams requires brief standalone pilot testing of questions, typically during a single 40 minute session.

For some parents, their children’s experiences with April’s tests seemed to solidify their decision to opt-out of the field tests.

Michelle Israel, who has a son in the fourth grade at Public School 107 John W. Kimball in Park Slope, said she had wanted to have her son boycott last month’s mandated tests. But she felt that the risk was too great.

“I felt that if it were something that were allowable, I would,” she said.

But her son’s experience during those two weeks of testing convinced her to remove him from the latest round of tests.

“On the second day of the exams he came out and burst into tears,” she said. Six days of 90-minute test sessions was too much for the children, Ms. Israel said. “They were fried.”

And she was not alone in having her child opt out of taking the science field test, parents said. Last week, about a third of the parents at P.S. 107 decided not to have their children participate, the parents said.

Parents in other schools had similar experiences. Martha Foote, who has a child at P.S. 321 William Penn in Park Slope said that during the two weeks of testing, her son had been grouchy and bored.

“He loves school,” Ms. Foote said, “and for those two weeks he asked if he could just stay home.”

Ms. Foote said she had feared that keeping her son out of last month’s tests would harm his school. Under No Child Left Behind, schools must have a 95 percent participation rate to satisfy their Adequate Yearly Progress, she said. “We wouldn’t do anything to hurt our schools.”

But with the field tests she had no such qualms. “There were no consequences,” Ms. Foote said. “They’ve had a good gig going with this data department.”

Jane Hirschmann, co-founder of Time Out from Testing, said that there were no known ramifications of boycotting the field tests. “Since they have no grade, they can’t be used for promotion, teacher evaluations, principal bonuses or a school grade,” she said.

She added that a borough assessment implementation director from Brooklyn had said that as long as intent was expressed in writing, parents would be allowed to opt their children out.

As a mother who kept her third grader out of last month’s tests, Diana Zavala is not directly affected this time, as the field test will only be administered to fifth graders at her son’s school, P.S. 206 Jose Celso Barbosa. But she has been active in persuading parents to opt out of a process she believes is invalid, she said.

“You are getting data from subjects who are not motivated,” she said. Ms. Zavala added that the convoluted questions and the lack of transparency and feedback on the field test made it a ridiculous exercise.

At Ella Baker School in Manhattan, only third graders are required to take field tests. But soon after hearing about the tests, they became the subject of a PTA meeting, said Dani Gonzalez, a parent who is on the PTA and the School Leadership Team.

Parents worked the phones and e-mail to discuss the issue and organize resistance, and about half of the third-grade parents said they were ready to keep their children out of the tests, Ms. Gonzalez said.

“Without our consent or advice the state education department has given our kids over as lab rats,” said Ms. Gonzalez, whose child is in the sixth grade. “If they wanted parents to provide kids for their data, they could pay for it.”