Rinse and cut off the ends of the rhubarb and chop into 1/2" pieces. If adding apples or strawberries, peel, core and slice the into bite size pieces. Place in a greased 13" x 9" baking pan.
In a mixing bowl beat the flour, sugar, baking powder, egg and vanilla until it becomes a crumbled mixture. Sprinkle this mixture over the rhubarb.
Melt the butter, drizzle over the top and sprinkle with cinnamon. Bake for 40 minutes.