"I can't believe we're still best friends." The murmurs rise as six high school seniors at The Classical Academy jostle their way to the elementary school playground to be photographed. The three guys and three girls bonded in kindergarten at The Classical Academy, or TCA, in Academy School District 20. An impressive 62 percent of the class of 2018 started in kindergarten and are graduating this month, said TCA spokeswoman Tisha Harris. TCA is the state's largest charter school, with 3,800 preschoolers through 12th-graders. "We're like a family," said senior Brady Miller.