Lady Gaga has surprised children at a high school in Hollywood by posing as a substitute teacher.

The Born This Way singer recently turned up at Walter Reed Middle School in Los Angeles, where she took a lesson as part of a campaign to raise funds to provide kids with school supplies.

After reassuring stunned pupils that she was, in fact, the real Lady Gaga, she asked students to show her what they wanted to be when they grew up.

"I want you to draw what is your future and what does it look like," she told the class.

The campaign has been organized by staff at Gaga's Born This Way Foundation and DonorsChoose.org, a non-profit which funds school projects and supplies.

Bosses at Staples, one of the sponsors of her forthcoming Joanne tour, have also donated $2 million to the cause as part of their Staples for Students program.

"I want kids to love themselves fearlessly," added Gaga. "Not having materials at school is a real problem."

Lady Gaga, real name Stefani Germanotta, founded the Born This Way Foundation in 2011 in order to help young people around the world.

Via her charity, she has funded campaigns to help victims of bullying and homophobia as well as those suffering from eating disorders.

Earlier this year (17), she teamed up with British royal Prince William to encourage people to talk about their mental health, admitting she has suffered from post-traumatic stress disorder after being raped at the age of 19.

The 31-year-old also previously collaborated with coffee retailer Starbucks to raise money for her foundation, surprising customers by working a shift as a barista in a Los Angeles store.