When Alice Van Ness started teaching yoga to Facebook employees at the company’s Menlo Park campus a few months ago, she didn’t expect to be taught a lesson.

And a costly lesson it was. The 35-year-old San Carlos resident was fired last month for trying to restrict cellphone use in her class.

“I understand it’s a busy world we live in and you’ve got to pack it in, but it’s beneficial to your whole system to let it go for an hour,” said Van Ness, who has been practicing and teaching yoga for six years. “An hour isn’t too much to ask.”

Although she tells her students before every class to turn off their cellphones, Van Ness said that in the middle of a Monday noontime class at Facebook, a female employee pulled out her phone and began typing during a half-moon pose. Though Van Ness didn’t say anything, she gave the student a “look of disapproval,” which the student later complained about to others.

“It’s not appropriate,” Van Ness said in explaining why she shot the student a stern glance. “It’s time to pay attention. I’ve even hurt myself in that pose. … I don’t believe there’s anything that could be going on at Facebook that couldn’t wait a half an hour.”

Two weeks later, Van Ness said she was called into a meeting with her supervisor at Plus One Health Management, with which Facebook contracts to oversee its onsite gym and fitness programs.

“They sent me packing, they didn’t even want to hear my side of the story,” Van Ness said. “They already had my paycheck ready.”

According to the termination letter, the employee said Van Ness had “made a spectacle of her” during the class by stopping instruction and glaring at her when she pulled out her phone.

Van Ness said she didn’t know the employee’s name or whether she is a high-level executive at Facebook.

The termination letter emphasized the company’s readiness to bend over backwards for its customers.

“We are in the business of providing great customer service, unless a client requires us to specifically say no to something, we prefer to say yes whenever possible,” Van Ness said, reading from the letter.

Just like that, Van Ness said she lost a third of her monthly income for weekly fitness classes in yoga, Pilates and spinning at Facebook and one yoga class for Plus One at Cisco Systems.

The incident, however, has made her a cause célèbre among yoga devotees and she’s already accepted new work teaching classes at another yoga studio.

Slater Tow, a Facebook spokesman, said because Van Ness is not its employee the company has nothing to say about the matter. Facebook does not require employees to keep their phones on throughout the work day, he said.

Officials for Plus One Health Management did not respond to requests for comment.

Email Bonnie Eslinger at beslinger@dailynewsgroup.com; follow her at twitter.com/bonnieeslinger.