[X is on the right side of your body.] = X is on this side of your body: Most people write using the hand they have on this side of their body.
[I use my right hand when I draw pictures.]
12-21. left.
[X is on the left side of your body.] = X is on this side of your body: Most people do not write using the hand they have on this side of their body. They write using their other hand.
12-20. right.
[X is on the right side of your body.] = X is on this side of your body: Most people write using the hand they have on this side of their body.
[I use my right hand when I draw pictures.]
12-21. left.
[X is on the left side of your body.] = X is on this side of your body: Most people do not write using the hand they have on this side of their body. They write using their other hand.
[My child held my left hand.]