Preheat your oven to 350 degrees.
Place the strawberries in a large casserole dish. Sprinkle on 1-2 teaspoons of Splenda or sugar, just to get the strawberry juices flowing. Let stand for 15 minutes.
Mix together the cake mix & soda. Pour on top of the strawberries. Bake for 30 minutes. Let cool for 10 minutes before serving. Garnish with fat-free cool whip if desired.