Mix together flour, sugar, baking soda and the cocoa.  Then add to this mixture, the water and mayonaise (or Miracle Whip) We like the taste of the Miracle Whip best.  Mix well.  Grease and flour bottom of cake pan.  Bake in a 350 degrees oven for 30 minutes until done.  I usually check the middle of the cake with a toothpick to see if done.  This is a really moist and good cake.  I like to use a buttercream icing on top. You can make this icing from scratch or buy it in the store already made. Another great tasting icing is the Betty Crocker White chocolate with almond. Very good!  Delicious!