At a time when morale among public school teachers has dropped to a 20-year low and many feel unfairly blamed for failing schools, Rebecca Mieliwocki has a message for the nation’s educators: Stand tall.

“You will never meet a more hardworking American than a teacher, it’s the best value your tax dollars can get,” said Mieliwocki, a seventh grade English teacher from Burbank, Calif., who will be honored Tuesday at the White House by President Obama as the 2012 Teacher of the Year. “I want them to stand up a little taller, be a little prouder and be very passionate about getting better.”

Mieliwocki said social and economic pressures have made her job increasingly more challenging since she began teaching in public schools 14 years ago.

“We face so many barriers to student success that I didn’t create and are beyond my control,” she said. “I can’t control whether my students eat breakfast, have a place to sleep at night, whether they have access to technology. I can do every thing I can when they step into my classroom to try to level the playing field but one person alone just can’t do it all, and that’s pretty overwhelming.”

Mieliwocki, 43, teaches in a racially and economically diverse middle school outside Los Angeles. The school’s students scored above the state average in math and English, according to the most recent data. About 43 percent of the school’s 1,010 students are classified by the state as poor.

“In any school system in any state, whether the most affluent district or not, you have families in crisis right now,” Mieliwocki said. “Everyone is worried about money, jobs, the economic future. I am seeing it in my classroom. I see the needs are so great — health care, hunger, transportation, clothing, parents losing jobs. It’s all hands on deck right now to get through this.”

At the same time, a nationwide shift promoted by both Republicans and the Obama administration toward evaluating teachers based on student performance has led some teachers to worry that their careers can be abruptly ended by poor test scores.

Test data should be just one aspect of a multi-dimensional evaluation process, Mieliwocki said.

“I am responsible for my students’ abilities and what they can learn and we test that knowledge once in a school year and I need that knowledge to help me improve as a teacher,” she said. “But if you only look at test scores, you will miss so much more that is directly responsible for the growth of young people. Please make sure that you’re looking at all of it.”

An annual survey of teachers by MetLife released in March found teacher job satisfaction has dropped 15 percentage points since 2009, from 59 percent who are very satisfied with their jobs to 44 percent, the lowest level in two decades. Meanwhile, the percentage of teachers who say they are very or fairly likely to leave the profession has risen 12 percentage points since 2009, to 29 percent from 17 percent.

The daughter of two public school teachers, Mieliwocki initially began a career in publishing after her graduation from California Polytechnic State University.

But the work left her uninspired. “So I made a list of the things I needed in my dream job: Be your own boss, work with children, try to leave the world better than when you were delivered into it,” she said.

When she shared the list with her husband, he told her “It’s so obvious. You’re supposed to be a teacher, silly,” she said. “And the minute I entered a classroom, it felt so natural, so normal, like a breath of fresh air. It was everything I wanted it to be.”