Usually, when your children are sick, it would be a good idea to get them to drink a lot of water (and not any water, but plan water) this is especially the case during the first day, because you try wash out the virus, within their body, before they even have an opportunity to multiplie within the children's body.
But sometime, it might be difficult to get some children to drink large quantity of water and giving them a beating won't necessary help, especially if the kid is ill it might not be a good idea to slap your kids, under such circumstances. In this instant try this trick. Add two tea spoon of sugar into ever sizable glass of water, that you want your kids to drink. Your children would love it, because it is sweet and they would gulp in down so quickly and ask you for more :)
It work with my dog, my neighbour's kids and cousin's kids too (I told them to try it this way), so maybe, this would work with your kids too. :)