My daughter has just started reception. I just wondered if she's old enough to give her a packet of tissues in her pocket and teach her to sneeze or cough in it then throw it away? It's hard enough to remind her to put her hand in front of her mouth though. I always had a packet of tissues in my pocket at primery school, but my Mum said I'd always come home with them un opened and snail trails up my sleeves.
The trouble with tissues is you sometimes sneeze quite unexpectedly and you don't have the time to fumble for one in your pocket or go to the box in the classroom. My DCs were taught last year in school (thanks to the swine flu) to sneeze into their elbows, then wipe or blow nose afterwards, then bin the tissue. Elbows are better than hands, because you never touch anything with the inside of your elbow.