Preheat oven to 350 degrees. Mix apples, 1/4 cup sugar, lemon juice, tapioca and cinnamon in large bowl. Let stand 10 minutes.
To make topping, stir crushed cereal, remaining 1/4 cup sugar and margarine in medium bowl until well blended.
Spread apple mixture in ungreased 1 1/2-quart baking dish. Sprinkle evenly with cereal topping. Bake for 45 minutes or until topping is browned and apples are tender when pierced with fork.