As I was tucking my 5-year-old daughter into bed last night, she explained that her younger brother (just turned 4) doesn't really understand the Trinity yet--he inclines toward tri-theism instead of Trinitarianism. She herself used to be a Modalist--but "sometimes it takes a while" because "it's hard for little kids to understand."
So grateful that the Trinity is no longer a mystery to her!
(No, she didn't use those terms, but she did use the concepts!)