Present-tense stem changes

What you’ll learn

• Recognize three frequent stem-change patterns.
• Keep regular present endings while changing the stem.
• Use unchanged nosotros and vosotros stems in the patterns taught here.

Change the stressed stem

Some present-tense verbs change a vowel in the stem while keeping familiar endings. Pensar gives pienso, piensas, piensa, pensamos, pensáis, piensan. Poder gives puedo, puedes, puede, podemos, podéis, pueden. In these patterns the stem changes when it is stressed; nosotros and vosotros keep the original vowel.

Learn a verb together with a representative changed form: querer—quiero, dormir—duermo, empezar—empiezo. Do not assume every e or o changes. The infinitive alone does not tell you the complete pattern, so record it when learning the verb. These changes belong to a particular tense and set of forms; later tenses need their own checks.

Pedir and useful verb combinations

Another common pattern changes e to i: pedir becomes pido, pides, pide, pedimos, pedís, piden. Servir follows a similar pattern in the present. Keep the stem change separate from the ending: pides has the tú ending -es, while piden has the plural ending -en.

After a conjugated querer or poder, use an infinitive: Quiero salir; podemos estudiar. For a request, ¿Puedes repetir? is more useful than practising poder alone. Jugar has its own u-to-ue pattern: juego, juegas, juega, jugamos, jugáis, juegan. Group examples by the pattern you actually need, then practise them in a small exchange.

Useful vocabulary

poder

to be able to

pedir

to ask for / order

empezar

to begin

Common mistakes

• Do not carry the changed vowel into podemos or pensamos.
• Keep the second verb as an infinitive in quiero estudiar.
• Pedir means to ask for something; preguntar means to ask a question.

Keep these ideas

• Common present changes include e→ie, o→ue and e→i.
• Nosotros and vosotros retain the original stem in these patterns.
• Learn each verb's pattern with a useful sentence.

Use it in your life

Give a story character something they want, something they can do and something they ask for. Use querer, poder and pedir.

Read it in context

Look for this lesson’s ideas in a complete Spanish story. Read the passage first, then use its translations to check your understanding.