Usually, if you stand still long enough, the dog will get bored and move on. Kids are too busy running around to realize they have worked up a sweat in the heat and humidity. Because of their immature nervous systems and a lack of awareness that they are getting overheated, they are more prone to heat-related problems such as cramps, heatstroke and exhaustion. Try to get children 10 and younger to drink at least a few ounces of water about every 30 minutes. You can also give them diluted fruit juices or even electrolyte formulas.
Older kids can probably go every hour and are more likely to keep tabs on their intake themselves.
Chances are, your camper is homesick, and that is perfectly normal. Ideally, you should send a letter ahead of time so that it arrives when your camper does. These statements will only make them feel worse. It's better to be positive and to let them know you love them. Your letters can include small items that remind them you are thinking of them, too, such as a pack of gum, stickers, puzzles or games.