How to cook perfect pasta every time:

In a large pot, heat 4 to 6 quarts of water to boiling for one pound of dry pasta. (You can adjust this amount depending on how much pasta you are cooking.) Add salt, if desired, allowing 1 tablespoon of salt for every pound of pasta.

When the water reaches a hard, rolling boil, add the pasta gradually, stirring at the same time. Allow the water to return to a boil. (Salt added to water is an optional ingredient, a matter of taste, not proper cooking.)

Stir the pasta occasionally during cooking, to prevent sticking. Do not cover.

Follow the package directions for cooking times. Each manufacturer has tested their brands and shapes for the best cooking times. If the pasta is to be used as part of a dish that requires further cooking, slightly undercook the pasta.

Use a long-handled fork or spoon to taste for doneness. Perfectly cooked pasta is "al dente," or firm to the bite, yet cooked through.

Drain pasta in a sturdy colander and toss immediately with sauce. (Do not rinse unless the recipe says to do so.)

MEASURING DRY VS COOKED PASTA

Serving eight for dinner and need to know how many cups of pasta a pound will make? Here are some general guidelines for measuring dry vs. cooked pasta. (Shapes may vary in size according to the manufacturer, so use these measurements as generalizations.)

8 oz. uncooked small to medium pasta shapes = 4 cups cooked
(Examples: Elbow macaroni, Medium Shells, Rotini, Twists, Spirals, Wagon Wheels, Bow Ties, Mostaccioli, Penne, Ziti, Radiatore, Rigatoni)

8 oz. uncooked long pasta shapes = 1 1/2-inch diameter bunch = 4 cups cooked
(Examples: Spaghetti, Angel Hair, Linguine, Vermicelli, Fettuccine)

8 oz. uncooked egg noodles = 2 1/2 cups cooked

PASTA SERVING SIZES:
Shapes may vary in size according to the manufacturer, so use this as general guide.

A Full Hand = Two Cups
The Food Guide Pyramid defines 1/2 cup cooked pasta as one serving. If you compare your hand to a plate of cooked pasta with sauce, you'll find that you're probably eating two cups of pasta, which means you're getting 3-4 servings of low-fat, high carbohydrate pasta in a single meal, at least half the recommended daily amount of grain foods.

A Quarter = Two Ounces Dry Spaghetti
Two ounces of dry long pasta bunched up in your hand, such as spaghetti, thin spaghetti, linguine or vermicelli, is about the same size as the diameter of a quarter. Two ounces of dry pasta yields about 1 cup of cooked pasta (two servings.)

Soure: National Pasta Association