According to an article in the latest Kids Life, here are symptoms of bad vision to look for in your child:

-double vision
-blur when looking at near
-headaches with near work
-words running together
-falls asleep reading
-omits small words when reading
-holds reading too close
-sees worse at the end of the day
-dizzy/nausea with near work
-head tilt/close one eye when reading
-difficulty copying from chalkboard
-write up/down hill
-misaligns digits/columns of numbers
-burn, itch, watery eyes
-poor handwriting
-clumsy/knock things over