There's no question that fresh fruit is the best mid morning / afternoon snack. But it's less than appealing after several hours in the lunch box when it emerges battered and bruised. Dried fruit is another option, however with health concerns such as asthma, hyperactivity, behavioural problems, and gastric irritation linked to consuming products with additive 220 used to preserve dried fruit, it's not to be consumed in excess. Fruit roll ups are another marketed "healthy snack" and while they are free of sulphites (220) they typically only comprise of around 25% fruit, and are bulked up with maize, high GI maltodextrin, hydrolysed oils and "natural colours" some of which are banned in other countries.
The investment of a dehydrator is the way to make sure your child gets a healthy snack supplying carbohydrate in the form of natural sugar for energy; fibre and antioxidants made from 100% natural ingredients.