Contrary to what you might think, some bread is quite easy to make as long as you have the right ingredients. Perhaps the most important ingredient is yeast, which causes bread to rise and gives it structure, and luckily there’s an easy way to tell if your yeast is still good before you begin baking.

If you find yourself on a quest to bake fresh bread, but you’re not quite sure if your yeast is still usable, there’s a simple method to test it. MasterClass recommends testing your yeast by mixing it with a tablespoon of warm water. After a couple of minutes, if you see foam, your yeast is ready for business.

Although it’s relatively simple to test whether your yeast is still usable, yeast is not good indefinitely. While active dry yeast tends to have a longer shelf life, both active dry yeast and instant yeast can be kept in the fridge for up to four months, and if your yeast is unopened, you can keep it in the freezer for up to two years.