Conjugating Stem-Changing Verbs in the Present Tense

Spanish has a group of verbs called stem-changing verbs. The stem of a verb is what you have left after you remove the infinitive ending (ar, er, or ir), so you see changes inside the stem of the verb for some of the subject pronouns. The changes, which are to a vowel in the infinitive, follow a pattern, which you can see in the verb jugar (to play):

Sometimes stem-changing verbs are refererred to "boot verbs" or "shoe verbs" because the shape of the shaded areas in the box above-the areas that contain the stem change-sort of resembles a shoe or boot to people with very active imaginations.

How do you know which of the infinitive's vowels changes? It's easy in a short infinitive, because it's the only vowel that is left when you remove the infinitive ending. But if you have a longer (three-syllable) infinitive, the way you find the vowel you have to change is to look for the last one that is left after you take off the infinitive ending. Let's look at a couple of examples. In each case, the vowel that undergoes changes is italicized and highlighted for you.

In the present tense, there are three kinds of changes: o or u to ue (jugar, dormir), e to ie (cerrar, entender), and e to i (pedir, servir). How do you know which change to perform on an infinitive? In your textbook and many dictionaries, you will find the change indicated in parenthesis after the infinitive:

It's important to be well practiced with regular verbs before moving on to the exercises with stem-changers.