Adding a little oil helps, but also stirring occasionally will keep it from sticking. I sometimes use a metal spatula to scrape the bottom of the pot as I cook the pasta, just in case something is down there. That said, usually a couple of strands stick anyway.
hmmm... i haven't figured out my secret in cooking pasta...
but i never had problem with it sticking to the pot... all i do is put the pasta once the water starts to really boil. then add a little oil and a pinch of salt.
Well, I don't add salt to my pasta water and I don't cover the pot completely.
I do add a bit of olive oil to the water after I pour in the pasta and I keep the pasta boiling, not simmering. Regular, gentle stirring is important, especially at the beginning, but you seem to do that.
Are you using enough water for the amount of pasta you are cooking? The pasta should have plenty of room to swim around.
Are you removing the pasta while it is "al dente" or letting it cook to the "spagoush" stage (aka "gushy" overcooked spaghetti)?
The pasta will continue to cook when you add it to the pan with the sauce, so it's important not to overcook it in the first stage.
I sometimes salt the water and sometimes don't; it depends on whether the sauce I'll be using has enough already. I also keep the water boiling. But when the pasta is cooked, it goes into the serving bowl and then the sauce is poured on top of it.
This isn't a new thread, but I thought I'd add a remark about cooking pasta.
I was married to an Italian for a decade, lived in the country for a couple years and learned a few things. Here are some observations:
The best tasting pasta is cooked with the lid off the pot, and is always cooked at the most vigorous rolling boil your stove can achieve. Salt is always added to the cooking water.
While some argue that this is done in order to raise the boiling temperature, a great deal of salt would have to be added to make a significant temperature difference.
Salt is added to season the pasta... and preferably sea salt. Salt added during the cooking phase will be absorbed into the pasta as it cooks, as opposed to salt sitting on top of the pasta and sauce afterwards.
Generally, food sticks to cooking surfaces because of uneven temperature distribution. In the case of a glass pot, this is probably the case. But, since pasta is cooked in water and ought not spend a great deal of time in contact with the cooking surface, I speculate that in this case the volume of water is too small in relation to the quantity of pasta.
Four to five quarts of vigorously boiling, salted water to one pound of pasta is the traditional recipe. If your water volume is right, and the boil is vigorous, your pieces of pasta will not stick together.
Adding oil to pasta cooking water is never done in Italy. Adding oil to the water coats the pasta pieces and prevents the pasta from cooking evenly. It also prevents the sauce from clinging to and being absorbed by the pasta during the most important cooking phase. This is...
When your pasta is nearly done to your liking (hopefully al dente), drain it. Do not rinse it. Reduce the heat under the pasta cooking pot to low and ladle a small quantity of sauce into the bottom. Immediately return your pasta to the cooking pot and gently stir to coat the pasta evenly with the sauce. Allow all free moisture to be absorbed, stirring very gently as if you are folding cake batter, until the pasta is done to your liking.
I have to concur with Aotearoa that lots of water is key. Also make sure you are buying a decent quality semolina product. I can't eat wheat pasta now but it was a staple for many years and I usually used an import called Barilla which is reasonably priced. I put at least a bit bit of salt in the water, but unlilke Aotearoa I added a tablespoon of olive oil. As I recall learning to cook pasta (which was more of a trick than anyone would think) it was essential to have lots of water at a roiling boil and a good pot. Mine is a Cuisinart 8 qt stainless steel pot which works well for many soups, making soup stock and on and on. Paying attention to the pasta is also very important. Drain and strain a little before it is completely done as it will continue to cook itself. I did not do the cold rinse process. Don't trust the package times. And different types of pasta (of which there seem to be hundreds) will take more or less time depending on the shape and thickness. But seriously, get a decent pot. If you take care of it you'll have a lifetime of good food. And never ever be afraid of learning.
After everybody's good advice I drug out my huge stainless steel pot. I hate having to clean it because it barely fits in the sink BUT it does hold much more water. I've been using it, with lots of water, and keeping the temp. high for a good rolling boil and my pasta has stopped sticking.