Whether you should cover a pot while boiling grains depends on the type of grains you're cooking and your desired results.
Here's a general guideline for you, so you can choose the most suitable way of cooking for you.
Let's start with the benefits of covering the pot.
Covering the pot while boiling grains can help retain heat and moisture, which can lead to faster cooking.
This is especially useful for larger or denser grains like rice, whole grains, and legumes.
Covering the pot can help ensure that the grains cook evenly and have a consistent texture throughout.
It prevents excessive evaporation, which can cause the grains at the top to become dry while those at the bottom remain undercooked.
Covering the pot helps prevent excessive water evaporation, which means you'll use less water overall for cooking.
Now, let's talk about not covering the pot.
Some grains, especially those that tend to foam or expand significantly while cooking, can cause the pot to boil over if covered.
Leaving the pot uncovered allows steam to escape, reducing the risk of overflow.
If you prefer your grains to be less mushy or sticky, leaving the pot uncovered can help achieve a drier texture.
This is often the case with pasta and some types of rice.
Cooking without a lid allows you to closely monitor the grains as they cook.
This is particularly useful if you're experimenting with a new type of grain or recipe.
If you're cooking grains in a sauce that you want to thicken, leaving the pot uncovered can help evaporate excess liquid and concentrate flavors.