Symmetry

Amelia:  Ice skates are normally symmetrical so when I dropped some purple paint on one skate I made sure to put it on the other skate also.

Me (stopping what I was doing and actually listening): What did you say?

Amelia repeats her statement and shows me the picture.

Me:  Where did you learn about symmetry?

Amelia (incredulous):  Pre-school!  And Kindergarten, of course!