Watch for those students who are sitting up on their legs. By pushing  themselves out of their reading space, they will be the students who make  more mistakes as they read later.   

Watch for those students who choose to continually stand to do their work.  They are not developing their reading space.   

The student who constantly looses things that are actually right in front of him, has poor spatial awareness and will make more mistakes reading.  This child would benefit by doing the two above things and playing hand  held games such as cards and Gameboy. Stringing beads is also good as  well as bouncing a ball.  

Encourage students to work on their centerline. (belly button) If you see a  child push his work to the right of his body, tilt his head awkwardly as  he works, or constantly lay his head down as he works, he is setting  himself up to have more trouble reading.