Al dente means "to the tooth," and it's the most-desired characteristic of cooked pasta in authentic Italian dishes. Some lasagna noodles don't have to be boiled before assembling the dish, but other gourmet pasta brands -- and whole wheat and whole grain varieties -- must be cooked for the lasagna casserole to be edible. When cooking noodles al dente, you must hang out at the stove and monitor the pot closely; otherwise, you can end up with mushy noodles.
Run just over a gallon of water into a pot that holds around 2 gallons of liquid, which is around 8 quarts. Typically, you need 1 gallon of water to boil 1 pound of pasta. But don't worry about precise measurements; pasta cooks properly as long as it's completely submerged in boiling water.
Bring the water to a boil and add a heaping spoonful of salt, which flavors the noodles as they cook -- the water should taste very salty. You may wish to add a spoonful of oil to the pot, which may keep the noodles from sticking together, but some chefs believe that oil keeps sauce from sticking to the pasta. Add the lasagna noddles to the boiling water a few at a time, but don't break them. They'll gradually slide under the water as they soften.
Let the lasagna noodles boil for about 10 minutes; stir the needles periodically, which keeps them from sticking. After 10 minutes, lift a noodle out of the pot with a fork and break off a piece to determine if it's al dente. Ensure that the noodle's outer layer is soft while its inner core is just a little bit stiff.
Drain the noodles in a colander. Avoid rinsing the pasta, as doing so can keep the sauce from sticking and absorbing. Lay the noodles on a piece of aluminum foil or wax paper, which keeps the pieces from sticking together until you're ready to assemble your lasagna casserole in a baking dish.