Everyone should know how to make gravy. It is just one of those things even if you are not a retro cook and never encounter gravy outside of Thanksgiving. Here are the basics:

Meat Gravy

To each ¼  cup fat and savory brown juice in the roasting pan, add ¼ cup flour and blend until smooth. Add 2 cups cold water or cooking water from boiled potatoes, or milk; stir constantly over direct heat while heating until it boils and thickens. Season to taste4. If a thinner gravy is desired, add more water. Gravy coloring or caramel gives a more attractive brown gravy, but usually does not improve the flavor.

Variation: To make gravy for braised meat or pot roast, which has a considerable amount of liquid in the pan, remove the meat and slowly stir into the simmering liquid enough flour-water paste to make gravy the right thickness. If it is too thick, add water, cooking water from potatoes or other vegetables, to give the desired consistency. Season to suit taste with salt and pepper.

Flour-Water Paste for Thickening Gravy, Etc.

Sprinkle 2 tablespoons flour over ¼ cup cold water in a small jar; cover and shake it vigorously until blended. This amount thickens 1 cup milk to a good average thickness when stirred in, brought to boiling point, and simmered 2 or 3 minutes.  The Modern Family Cookbook