ELIZABETH — Tracy Espiritu's first hint that there was something unusual going on at the Monday morning assembly was when she spotted one of her former students sitting in the audience.

Then a guest from California took to the podium, promising to share a secret with the students of Dr. Albert Einstein Academy School No. 29.

Philanthropist Mike Milken told the school's more than 800 students that one of their teachers had been chosen to receive the Milken Educator Award, a $25,000 prize given to exemplary elementary and secondary school teachers, principals and specialists.

Espiritu today became one of 40 educators nationwide to receive this award this year.

The announcement, made during an assembly billed as a celebration of the school's STEAM — science, technology, engineering, architecture and math — curriculum came as a surprise to Espiritu, who was selected in secret by a committee.

Even as New Jersey First Lady Mary Pat Christie introduced the winner, detailing a background Espiritu recognized as her own, the science teacher didn't quite believe it, she said.

Christie described a woman who first worked in the private sector as an engineer, has launched after-school programs focusing on students and their families, and "graces us with her ingenuity and her forethought of what really makes students engage and makes them learn."

"At first I was like, not me," Espiritu said. "Then I turned to the teacher next to me, and she said, 'They're talking about you.' But I thought they must be talking about someone else."

Receiving the award on her birthday, Espiritu was also presented with a cake as the school choir sang "Happy Birthday" to her.

Espiritu, who grew up wanting to be an astronaut, started her career as an aerospace engineer. After getting laid off, she decided to make a change, go back to school for a second master's degree and become a teacher.

"My first month, I didn't think I was going to survive," she said. "Nobody ever thinks that teaching is hard. They really don't, but having that perspective really gives you the enlightenment that you're doing it for something that's worth it."

In addition to her classes, Espiritu created the Einstein Astronaut after-school program, teaching students in grades five through eight about space exploration. She has coordinated events designed to get parents involved in the learning process, including Astronomy Night, the Family Engineering Design Challenge and trips to the Liberty Science Center.

According to the Milken Family Foundation, Espiritu's efforts are a major contributor to the school's academic success, with 80 percent of students scoring proficient or advanced proficient on math assessments.

“The idea behind these awards is that everyone likes to hand out prizes to our heroes,” Milken said. “We give Grammys to musicians, gold medals to Olympians, Nobels to scientists and others. But we give too little recognition to the people with society’s most important job: educators. Nothing assures the success of a nation more than education, and nothing assures the quality of education more than dedicated classroom teachers instilling a love of learning and sense of wonder in their students.”

School officials and students said that Espiritu's commitment to her students is evident.

"As I visit schools, you walk into some and you can just feel the energy," Board of Education President Tony Monteiro said. "And you meet some teachers, and it just oozes out of them, the passion and the love they have for teaching. That's how she is."

Jonathan Hernandez, a former student of Espiritu's who is now a senior at Elizabeth High School, said he knows her classes left a lasting impact on him. He is now applying to study mechanical engineering in college and came to the assembly before an admissions interview.

"I loved her enthusiasm," Hernandez said. "She always brought something interesting to the classroom."

Espiritu said her students' enthusiasm inspires her and that watching them enjoy themselves in the classroom makes her job fun.

"You go into teaching not looking for any recognition, but when you do get recognized, it's very emotional," she said, wiping away tears. "All the hard work you put in — someone was noticing."

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Katie Lannan may be reached at klannan@njadvancemedia.com. Follow her on Twitter @katielannan. Find NJ.com on Facebook.