Found this article on Yahoo new. Thought it was pretty interesting:

8 Study Snacks That Make Kids Smarter
Posted Mon, Aug 20, 2007, 9:36 pm PDT
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Ask any kid, second-grader, or swaggering senior: Studying makes you hungry! Memorizing math formulas? Chips and soda are part of the equation. Digging into Moby Dick? Harpoon a bag of M&Ms.

Actually, the idea's right on -- eating can help the brain focus, if you know which foods to choose. But gee, surprise, candy and chips aren't among them.

What will help kids who are cracking the books? It depends on what kind of help they need, but it comes down to one of two Cs:

Carbs, healthy ones, for kids who tend to get so freaked about surprise tests or tough teachers that they lose all focus.
Comfort foods for studiers who start out okay but gradually get tense, can't sleep, wake up exhausted, and then don't do well.

Of the two, only one needs a little explaining: carbs. The brain needs glucose, or blood sugar, to stay sharp and alert. In fact, the brain is the only organ in the body that uses only glucose for energy. Glucose comes from carbohydrates. But the brain (like the body) does much better with a steady flow of energy, not the quick rush it gets from eating rapidly absorbed carbs like candy and chips. So slowly absorbed carbs -- which, gee, more surprises, include whole grains, fruits, and veggies -- produce longer lasting mental energy.

What's more, in addition to supplying the brain with energy, healthy carbs also have a steadying effect, explains Mindy Hermann, RD: They help boost serotonin, a calming brain chemical. And that combo -- calm energy -- is an ideal mix for many study-stressed kids, especially an hour or two before an exam or chem lab. So what to feed the homework harassed?

FOR STUDIERS WHO START OUT STRONG BUT END UP STRESSED AND SLEEPLESS, TRY:
A cup of something warm and soothing. Whether it's a light soup, warm milk, chamomile tea, or diet hot cocoa (to avoid the sugar hit) is personal preference -- all can help kids who've gotten tightly wound up to settle down again, says Hermann. Offer these about an hour before bedtime.

FOR KIDS WHO CAN FREAK OUT OVER HARD TEACHERS OR POP QUIZZES, TRY:
Apple slices spread with peanut butter. The carb-rich fruit will give serotonin a boost, which helps calm raggedy nerves so it's easier to focus. The peanut butter is filled with healthy fats.
Cheerios or other oat "Os" cereal. A big bowl of these to munch and crunch on can be a great study snack. This whole-grain kid favorite delivers a lot of nutrients as well as slowly absorbed, subtly calming carbs.
Grapes. Like apples, these sweet carbs get serotonin going while their high fiber content slows down sugar absorption -- plus fiber itself seems to have stress-soothing abilities. Some kids prefer their grapes frozen for melt-in-the-mouth fun.
Whole-wheat pretzels. They have the same crunch as regular pretzels but loads more fiber and often lots less thirsty-making salt, so studiers aren't constantly breaking their train of thought by wanting yet another drink.

More than good grades are on the table here, by the way. Kids who get into the habit of eating plenty of fruits and vegetables --aka healthy carbs -- are likely to keep it up into adulthood. If they do, their RealAge could be 36 when they're actually turning 40. Smart.