Best snack idea I have done for a class Valentine party is a chocolate (if school allows) fondue fountain and provide cut up fruits (bananas, strawberries, cantaloupe, and even rice krispie treats, and pretzels). Provide party skewers for the kids to poke into the snacks in order to dip them in chocolate, or have the skewers in them ahead of time. If you don't have a fountain, you can heat chocolate in the school's microwave and pour it into small cups for dipping. Other options are fruit pizza, yogurt cups with various items they can stir into it (fruit, fruit chews, grape-nuts cereal, etc), or use a heart-shaped cookie cutter to cut out small heart shaped sandwiches. For games, have relay teams race to pop Valentine colored balloons (100 of them maybe?). You can set rules for just how the balloons can be popped (sitting only, one foot only, etc). Craft ideas would be to have them decorate a Valentine mailbox (shoebox) or Valentine gift bag to put the Valentines in that they receive. Provide constuction paper hearts, doileys, stickers, glue, markers, etc. Sorry, I don't have many ideas for working the 100 in there!