Mark initially thought his son had been set a "trick question" so shared it to social media in the hope of finding the answer.

However, for many parents, helping their kids with homework ... Common Core math emphasizes “problem-solving, collaboration, and embedding concepts in real-life examples,” she says.

It's flattering when your kids are little, they think you know everything, until you try to help them with their math homework. "She tells me, 'Mom, Mom, this is not correct,'" said Virginie ...