Several types of noodles are available for lasagna; some lasagna noodles need to be boiled before you bake a lasagna, whereas others do not. Fresh noodles (or homemade noodles) do not need to be pre-boiled, and neither do dry noodles labeled "oven-ready." Traditional dried pastas need to be boiled before you assemble and bake your lasagna. If you prepare your lasagna properly and add plenty of sauce, your noodles should be done after baking for 40 to 60 minutes.
Boil your noodles before you assemble your lasagna if you are using a conventional dried variety: Boil noodles for 5 to 7 minutes, or until they are flexible. The noodles will continue to cook in the oven, so they should not be fully cooked at this stage. Your noodles are done when the pasta moves easily but is still chewy and dense in the center. Drain the noodles and cool slightly before assembling your lasagna.
Assemble your pasta, sauce and fillings in the lasagna pan. The moisture from the sauce will help cook your noodles (it is especially important to have plenty of sauce if you are using oven-ready dried noodles). Place the assembled lasagna in a pre-heated oven, covered with tin foil.
Bake the lasagna for 40 to 60 minutes, according to the recipe you are using. When the noodles are cooked through you will notice the sauce boiling around the edges of the pan. Insert a toothpick into the lasagna. If the toothpick goes in easily without a lot of resistance, the noodles are done, and your lasagna is ready.