How do you know whether or not your iOS app is going to be a hit? Getting an email from Steve Jobs is probably a strong indicator.

Ashish Toshniwal, the 31-year-old CEO of app design firm Y Media Labs, told Business Insider about how one of the first iPad apps his startup helped create impressed the late Apple CEO and co-founder.

Y Media Labs works with an education app startup called Montessorium.

The company creates individual apps that focus on teaching children how to write letters, learn basic math skills, and familiarize themselves with geography among other subjects.

When the iPad initially launched in 2010, there weren't many interactive apps that really took advantage of the tablet's touch screen, Toshniwal said.

According to the Y Media Labs CEO, Montessorium was ahead of the competition in that aspect. For example, the handwriting app provides a full-screen view of the letter and demonstrates the correct way to trace the letter before asking the user to do the same.

"When you look at this app, it was designed very cleanly," Toshniwal said. "It does a few things. The entire real estate [of the screen] is dedicated to teaching the kid how to write the letter ‘p’ for instance. And that’s what he [Jobs] loved about the app."

Shortly after Montessorium began creating apps in 2010 with help from Y Media Labs, Toshniwal recieved an email from Jobs, which said the following:

"I love what you are doing. Thank you. Let me know if we can help."

Montessorium's apps have since been featured in Apple commercials as well, Toshniwal said. Although Apple was a fan of Y Media Labs' and Montessorium's work, the app was relatively controversial around the time it launched.

Montessori, the teaching method from which the company's name is derived, heavily focuses on giving children freedom of movement within the classroom and allowing them to learn concepts by working with objects rather than reading from a textbook.

This, in turn, led Montessori enthusiasts to believe than those principles shouldn't be so closely associated with technology.

"Montessori by definition should not leverage technology," Toshniwal said. "It’s a very old school type of teaching. When it was launched, some of the Montessori experts were saying this was going to cause brain cancer or something like that. It was a really stupid and weird type of comment."

Y Media Labs' customers then reached out to Apple to alert the company that Montessorium was receiving so much backlash.

Jobs then offered Toshniwal a crucial piece of advice.

"His [Jobs'] comment was just keep doing what you're doing," Toshniwal said. "The users will prove them wrong."