Whether teaching basic addition or advanced physics, many educators pursue careers in education to realize the rewards of giving students skills they can independently use for the rest of their lives. While some teachers spend their entire young adulthoods preparing for their dream job, many go back to the classroom after long careers in other industries.

Penny Mudd spent nearly two decades adding expertise in the technology field to her already impressive resume, the San Francisco Chronicle reports.

Working in partnerships with European companies, designing her own software and gaining business experience with a small start-up firm, Mudd seemed to be fit for a lengthy career as an IT expert.

But after being fired by the start-up in 2007, the computer scientist faced a career crisis. She told the news source, "I had no choice but to re-evaluate my earlier daydreams in light of these changed circumstances and start building a new professional identity from scratch at age 50."

Now holding down a job as a teacher's aide and pursuing a degree in education, Mudd says, "With two careers in my arsenal, I look to 2010 with a spirit of adventure and a curiosity about what the future holds."

U.S. Secretary of Education Arne Duncan estimates that 1.7 million new teaching jobs will be needed by 2017.