Preventing Noodles from Sticking to the pot

When noodles or pasta is cooked in too little water, the starch released during cooking has nowhere to go, hence the stickiness.

If you are cooking plain noodles or macaroni, I would use at least twice the volume of water to noodles, preferably more depending on the size of pot available to you.

If you are cooking the "instant" variety that comes in a packet with pre-made flavourings, I would follow the package instructions but use a lower heat setting on your cooker, and ensure you give them a stir every so often. That way, the sauce will not thicken or evaporate so quickly.

While Greybeard's answer is correct in any regard, if you want to make the now so trendy one-pot-pasta this of course is not an option. Here, in a best case scenario, you have exactly the right amount of water/liquid for the noodles to absorb and to result into a creamy sauce. The starch the noodles release is used to thicken the sauce, which of course is prone to sticking or even burning to the bottom of your pot. This method isn't as easy as many cooking videos (especially on youtube) want you to believe, but if you stir often enough (for some thick sauces even constantly) it shouldn't be too much of a problem.

Both Greybeard and Gretel are right. You need plenty of water (because pasta expands as it cooks and absorbs water), probably a lot more than you're using (at least 3 times as much as if you were making rice, for instance). AND you need to stir. In my experience, stirring early is the most effective. You put the pasta in, you stir a couple times by the time the water is back to a roiling boil (that's another point, no simmering here). And then you stir really well before you let it really cook. Keep stirring every couple minutes. I'm not saying you have to stand there and stir the whole time like it was polenta, but you really have to keep it moving, that's what keeps your pasta from lying wanly at the bottom of the pot and sticking to it.