Kelly Clarkson is a Grammy-winning singer, a popular talk show host and a champion coach on The Voice. She is not, however, a teacher. After more than a month of living on her Montana ranch in an efficiency cabin she shares with husband Brandon Blackstock, 43, kids River, 5, and Remington, 4, and stepson Seth, 13, and their schoolwork, she’s struggling. “They’re insane. Everyone is insane,” she’s confessed. “Nine times out of 10, my kids are losing it ’cause they have to do school, which is somehow a shock every day, as well as nap time. It’s super fun.” Adding to the stress? She’s selling two homes at once: In May, Kelly, 38, listed her LA home for nearly $10 million. Her Tennessee mansion is also on the market for…
