25 percent of a quarter

When Christy´s older sister is doing her math homework, she asks their dad:
"What´s 25% of a quarter"
"25% is already a quarter. You can´t have a quarter of a quarter. That´s nonsense."
Then Christy scrambles across the floor and starts scibbling something on the floor with a piece of chalk held by his left foot. They guess it´s a Y or an X, but he´s really trying to write one sixteenth. He just can´t get the 6 right. They dismiss the attempt. He´s just not all there.... Heartbreaking...