President Biden's plan to reopen schools within 100 days has faced opposition from teachers unions due to coronavirus safety concerns, leaving other teachers frustrated.

"For the past year, there has essentially been a national teachers union strike that has left tens of millions of families without access to an adequate education," said Tommy Schultz, vice president of the American Federation for Children, a nonprofit supporting school choice programs.

Schultz cited numbers from October 2020 showing that roughly 3 million children haven't had a day of education since last March, "completely falling through the cracks."

"This will haunt our country for decades to come, and the teachers unions' blatant refusal to disregard science in the name of political extortion is outright shameful," he said.

Rebecca Friedrichs, who was an elementary school teacher in California for 28 years, echoed Schultz's concerns for U.S. children and the state of their education.

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"Most good teachers are deeply troubled by the strikes," she said. "We never want to deny the children even one day of learning, and we understand that we are servant leaders to those children."

Chicago Teachers Union leadership list their demands and leave a box of coal outside the entrance of City Hall following a car caravan where teachers and supporters demanded a safe and equitable return to in-person learning during the COVID-19 pandemic in Chicago on Dec. 12, 2020. (Photo by Max Herman/NurPhoto via Getty Images)

Chicago Teachers Union leadership list their demands and leave a box of coal outside the entrance of City Hall following a car caravan where teachers and supporters demanded a safe and equitable return to in-person learning during the COVID-19 pandemic in Chicago on Dec. 12, 2020. (Photo by Max Herman/NurPhoto via Getty Images)

Friedrichs is also a former union representative and was the lead plaintiff in the 2016 Supreme Court Case, Friedrichs v CTA, the case against the National Education Association and the California Teachers Association, which sought to give teachers and other public employees the right to decide for themselves whether or not to fund unions. The case lost after the U.S. Supreme Court deadlocked in a 4-4 decision and the Ninth Circuit Court of Appeals ultimately ruled against it.

Friedrichs said unions are using strikes to "push their muscle," and essentially pressure communities into meeting their demands, sometimes at the expense of children's education.

"Unions use these tactics on good teachers and threaten their jobs and peace on the job," she said. "So most teachers participate in strikes only to 'go along to get along.'"

Lisa Disbrow, an elementary school teacher in California with 34 years of experience, agreed, saying that teachers stay in the union because they're afraid of the union response to them leaving.

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"They've been told that no one else will take care of them, no one else will protect them," she said. "They're surrounded by people pushing in on them and trying to undermine a focus on academics, quality classroom management and a pursuit of real academic growth as the whole spectrum of agendas and indoctrination platforms swoop in. It's very politicized."

Teachers and PSC CUNY union members hold signs during a strike outside Hunter Campus High School in New York, U.S., on Wednesday, Sept. 16, 2020. (Photo: Paul Frangipane/Bloomberg via Getty Images)

Teachers and PSC CUNY union members hold signs during a strike outside Hunter Campus High School in New York, U.S., on Wednesday, Sept. 16, 2020. (Photo: Paul Frangipane/Bloomberg via Getty Images)

Willie Preston is the father of six children who all attend public schools in Chicago. He said said his children’s teachers and Chicago public school teachers in general are "very afraid" to speak out publicly because the Chicago Teachers Union (CTU) is a "very unforgiving organization."

"I don't know if a CTU member even those against what's going on would be willing to publicly speak out," he said. "CTU has teachers reaching out directly to parents for making social media statuses that don't align with their views. These teachers won’t be saying anything."

Karen Cuen, an elementary music teacher for over 25 years in the Chino Valley Unified School District in California, believes other teachers are frustrated with their unions too, because schools need to reopen.

"Teachers unions are never correct to strike," she said. "Teaching is not just a job, it’s a calling. Our ‘clients’ are precious children who deserve to have their teachers teaching them, not walking a picket line."

Cuen said she understands workplace issues and the need for bargaining power, but said that some union demands to reopen schools "are often not even related to education."

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"We have been told to ‘follow the science,’ which increasingly points to opening schools, yet politics seems to rule at every turn," she said.

The Centers for Disease Control and Prevention (CDC) has said that schools can open for in-person learning without teacher vaccines "even in areas of the highest community spread" with proper safety precautions.

"We have a consensus among non-political medical experts, including top CDC leaders who wrote in the top medical journal, JAMA, three weeks ago that schools do not contribute to transmission — a position that contradicted the official CDC guidelines," said Dr. Marty Makary, a physician and professor of medicine at Johns Hopkins University, as well as a Fox News Contributor.

Dr. Janette Nesheiwat, a family and emergency medicine doctor and Director of CityMD and Fox News contributor, agreed.

FILE - In this Jan. 11, 2021, file photo, pre-kindergarten teacher Sarah McCarthy works with a student at Dawes Elementary in Chicago. (Ashlee Rezin Garcia/Chicago Sun-Times via AP, Pool, File)

FILE - In this Jan. 11, 2021, file photo, pre-kindergarten teacher Sarah McCarthy works with a student at Dawes Elementary in Chicago. (Ashlee Rezin Garcia/Chicago Sun-Times via AP, Pool, File) ((Ashlee Rezin Garcia/Chicago Sun-Times via AP, Pool, File))

"I understand the fear teachers may have," she said, "however let’s look at the data, and the science which shows transmission of COVID-19 in the classroom is less than that in the community. I think we need to support our teachers and allow them to have access to vaccinations so that they feel safe returning to the classroom."

"The CDC already issued school guidance in September. The Biden administration's call for another updated set of guidance stalled the reopening of schools and resulted in more pediatric suicide, worsened the child hunger crisis and created other health problems in children," he said. "The overly onerous requirements for schools in the CDC's guidance has further stalled school reopenings and further harmed children. Time is lives."

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Preston said he wants his six children to be able to return to school in Chicago for multiple reasons, but principally that "the science from the CDC and others says schools can reopen safely as long as mitigation policies are put in place, which the Chicago Public School system has done."

"In fact, CPS spent nearly $100 million to set CPS classrooms up to be safe," he said.

Preston believes it is possible for Biden to achieve his goal of reopening schools in his first 100 days if he stands behind science and "stands up for American children and their families, and does not allow education to become a political fight."