. >> reporter: 8-year-old arkinia graham has never met her father. they've grown close over the phone. but johnny tre williams is serving 23 years in prison for second degremurder. >> i'm excited to see you and i'i' nervous. >> reporter: today she and nearly 30 othth kidid are getting a spepeal visit with their dads designgn to prevent the kind of damage kids suffer when a parent is in pron. >> they're going to have fun -- >> yes. >> reporter: they are some of the nearly 3 million children in this country with a mom or dad behind bars. ethan buckner is 7. >> you're going to see your dad today? >> reporter: maya matthews is 9. she and her little brother live three hours away. >> so how excited are you to see your dad? >> very. like, i can jump super high. >> you're so excited, i know. >> my dad -- >> she's here, do you wa to meet her? >> reporter: maya has visited befo but today is different. >> arkinia, i want you to meet maya. she heard about you. >> meeting your dad behind bars is a really big deal. >> why is it a big deal? >> like this is the one