I realized yesterday that Princess is now 5 years old and Little Buddy is now 4 ... and I don't think either one of them knows their "right hand" and "left hand."
So, I grabbed one of my ever-at-the-ready Sharpie markers and wrote an "R" on their right hands and the top of their right foot and an "L" on their left hands and feet. I placed them in front of me, facing the same direction, so that the letter is correct from their viewpoint.
Throughout the day, I asked them which was their "right hand," "left foot," etc. I'm hopeful that a few days of this will teach them which is which!