When Matthew Gross saw his second-grade son struggling to read, he knew he wanted to do something to make learning more engaging and fun.

At the time, the former teacher was working for Regents Research Fund, which was helping to develop the Common Core education program for New York State and he was growing frustrated by the textbook publishers that failed to keep up with the new curriculum.

In 2013, he launched Newsela, an education startup that rewrites news articles, historical speeches and scientific papers for students at different reading levels to help them learn to read.

The online program is free for students, but a paid premium version is available to schools. In April, Newsela announced it was expanding its premium version to include a program that helps foster students' social and emotional learning skills.

Today, Newsela says its software has been used by teachers in over 90% of K-12 schools in the US.

Related: Newsela is using journalism to make kids better readers

CNNMoney asked Gross about the challenges of running a startup and his advice for aspiring entrepreneurs.

My inspiration for Newsela came while I was ...

Working on rolling out Common Core standards in New York State. Common Core presented a major shift in thinking for what should be covered in schools and how.

Here was a golden opportunity to rethink education content to be more engaging, accessible and relevant to kids' lives, so it astounded me that old textbooks claimed to meet the criteria of the new standards without changing a thing. Big education publishers were just giving us the same outdated textbooks, some with an orange sticker that said "Common Core-Aligned!" (literally).

I wanted to make a bigger impact, but I was deathly afraid of starting a new venture, given the checkered history of education startups.

About the same time, my middle son Curtis was struggling with reading. On New York's scale of 1 through 4, he was a 2, which meant he wasn't on track.

I met with his assistant principal, who was evasive and said something I will never forget: "We'll do what we can, but some kids are just going to be a 2." I felt like she gave up on him.

I decided to start Newsela that day.

The scariest part of my job is...

Hiring. Each new member of the team can have a profound impact on the teamwork and social dynamic of the company. It's nerve-racking to imagine the drama that can come from one bad employee.

We carefully screen candidates for culture fit, as well as expertise and a history of outperformance. Every candidate goes through our hiring committee. If two members of the committee reject the candidate, generally they don't get hired.

If I could tell my 18-year-old self one thing, it would be ...

Get a job for a while. You're burnt out on school. Go to college when you have a burning desire to learn more.

The thing that brings me the most joy is ...

Hearing from teachers. A few times a year, I email our 1.3 million teachers about a topic I find important. I generally get hundreds of emails back.

Sometimes they thank us for making content more relevant for their kids or making it possible to get reluctant readers to discover the joy of reading or making it easier to teach emotionally charged topics. I try to read and respond to almost every email I get.

Sometimes it's tough, like when I email teachers about upcoming articles covering school shootings. The things teachers share can be heartbreaking.

If I could have dinner with any influential figure from any time period, it would be with ...

Daniel Kahneman, winner of a Nobel Prize for his work in behavioral economics and author of "Thinking Fast and Slow."

He's most famous for identifying dozens of systematic biases that affect our judgment and decision making. What's amazing is how many business leaders know about these biases and do nothing to identify or counteract them. The impacts can be disastrous, even fatal.

I'd like to be remembered for ...

Helping to make the engagement, relevance and love of learning the focus of education.

There's no rule that says school must be an institution of boredom and suffering. Standardized test scores may be necessary, but they shouldn't be the endgame.

The thing you probably don't know about me is ...

I started my career as a music teacher.

I was a music composition major in college, though I was never required to learn an instrument. I may be the only music teacher in the history of New York City public schools who couldn't play the piano.

If I weren't CEO of an education company ...

I'd be a pop music recording engineer.

I'm fascinated by music samples, unusual sounds, how a song rises and falls, tricks of the ear. Unfortunately, I go to bed at 10, which is about when a lot of pop artists are just getting ready to head into the studio. I'd probably fall asleep on the mixing board.

The best piece of advice I've ever received is ...

From John King, who was my boss in New York State while I was Executive Director of the Regents Research Fund. He later became Education Secretary. He said, "You're like a dog with a bone."

It wasn't a compliment.

The message was that you have to pick your battles, and even when you've gone to battle, unyielding tenacity isn't always the way to win.

His favorite example was a battle over tissues. There was a policy at the State that employees were responsible for buying "personal items." When I tried to buy tissues for my team in the heart of a miserable, flu-ridden winter, the finance department denied the purchase because tissues were considered personal items.

I started a war with the finance department and the COO. What could I have instead accomplished for the kids of New York with the time and treasure I spent on Kleenex-gate? We'll never know.

My advice to people searching for their inspiration is ...

Find a job somewhere that has a mission -- one that the leadership actually lives and breathes. Once you're on the team, you'll feel like you're part of a movement and you'll never want to go back to a soulless job again.