I made two today- PIECE OF CAKE! and figured while I was making some I might as well do a tutorial. So here ya go...
-length of bias tape (I used about 14in for 1 shirt)
find a slightly over sized long sleeved t-shirt. (I used a 3t) This one was pre-stained (came out of the hand me down box!)
turn the shirt over- backside up and cut directly up the middle.
step 3) sew on bias tape "ties" to the neck
I laid it down like so and stitched it down about an inch and a half- make sure you re-enforce it.
step 4) pin down sides, edges turned under to keep fraying to a minimum
step 5) stitch sides down
step 6) I had to hand sew around the ties because it was too thick for my machine, so finish up whatever you need to by hand
here's the other smock I made at the same time: