Mix together dry ingredients. Cut in shortening (or margarine) with 2 knives or pastry blender, until mixture is the consistency of coarse cornmeal. Make a well in centre and add milk slowly.
When all the milk has been added, stir dough rather vigorously until it comes freely from the side of the bowl.
Turn dough onto lightly floured board and knead lightly for a few minutes. Roll or pat out to desired thickness (about ½ inch). Cut dough with 2 inch floured biscuit cutter; place on ungreased baking sheet.
Bake in in a hot oven (450 F) for 12 to 15 minutes. Makes 15 to 19 biscuits.