Our topic for this session:

 

Conjugating the following -AR, -ER and -IR verbs
that have e to ie stem changes in the present tense:

  • pensar
  • querer
  • preferir

Using these 3 verbs followed by an infinitive to express planning, wanting and preferring to do things.

Remember, with stem-changing verbs, what makes them special is that, instead of leaving the stem alone after we derive it (by removing the -AR, -ER or -IR infinitive ending),
whenever the subject is NOT nosotros (or vosotros, but we won't use vosotros-forms in this course),
we change the stem vowel in a certain way.

Once that change is made, then we add the right conjugated ending for the sentence's subject.

As always, when conjugating, we're only concerned with 2 things: 

  • stem  
  • ending

For regular stem-changing verbs (like "pensar", "querer" and "preferir"), the only form that doesn't show a stem change is the nosotros-form:

infinitive: pensar

nosotros-form: pensamos

conjugated ending is "amos"

infinitive: querer

nosotros-form: queremos

conjugated ending is "emos"

infinitive: preferir

nosotros-form: preferimos

conjugated ending is "imos"

In the other 4 present-tense forms, the stem "e" has to change to an "ie" before we can add a conjugated ending.

Once that change is made, then we add the right conjugated ending for the sentence's subject.

The 4 forms of -AR verb "pensar" where the stem "e" changes to "ie" are:

tú form: piensas
changed stem is "piens"

conjugated ending is "as"

3rd-person singular: piensa
changed stem is "piens"

conjugated ending is "a"

3rd person plural: piensan
changed stem is "piens"

conjugated ending is "an"

yo form: pienso
changed stem is "piens"

conjugated ending is "o"

The 4 forms of -ER verb "querer" where the stem "e" changes to "ie" are:

tú form: quieres
changed stem is "quier"

conjugated ending is "es"

3rd-person singular: quiere
changed stem is "quier"

conjugated ending is "e"

3rd person plural: quieren
changed stem is "quier"

conjugated ending is "en"

yo form: quiero
changed stem is "quier"

conjugated ending is "o"

The 4 forms of -IR verb "preferir" where the stem "e" changes to "ie" are:

tú form: prefieres
changed stem is "prefier"

conjugated ending is "es"

3rd-person singular: prefiere
changed stem is "prefier"

conjugated ending is "e"

3rd person plural: prefieren
changed stem is "prefier"

conjugated ending is "en"

yo form: prefiero
changed stem is "prefier"

conjugated ending is "o"

All together, here are these 3 verbs in the present tense (conjugating really is just stem + ending):

  • yo form (stem change): pienso, quiero, prefiero
     
  • tú form (stem change): piensas, quieres, prefieres
     
  • 3rd-person-singular form (stem change): piensa, quiere, prefiere
     
  • nosotros form (never a stem change): pensamos, queremos, preferimos
     
  • 3rd-person-plural form (stem change): piensan, quieren, prefieren

You can see all these conjugated forms on textbook pages 149 and 151.

Use conjugated "pensar" plus infinitive to express that you're thinking about doing or planning to do something (or that someone else is):

  • Pienso estudiar mucho esta noche. (I'm thinking about studying/planning to study a lot tonight)
     
  • Pienso hacer ejercicio mañana. (I'm planning to exercise tomorrow)
     
  • Mi abuela piensa tomar una siesta por la tarde. (My grandma is considering taking a nap this afternoon.)

Topic 2: Using these 3 stem-changing verbs plus infinitive to express planning, wanting and preferring to do something.

Use conjugated "querer" plus infinitive to express that you want to do somthing (or that someone else does):

  • Quiero estudiar mucho esta noche. (I want to study a lot tonight.)
     
  • ¿Quieres hacer ejercicio mañana? (Do you want to work out tomorrow?)
     
  • Mi abuela no quiere tomar una siesta por la tarde. (My grandma doesn't want to take a nap this afternoon.)

Topic 2: Using these 3 stem-changing verbs plus infinitive to express planning, wanting and preferring to do something.

Use conjugated "preferir" plus infinitive to express that you prefer to do somthing (or that someone else does):

  • Prefiero estudiar esta noche. (I prefer to study tonight.)
     
  • Prefieres hacer ejercicio por la mañana, ¿no?. (You prefer to work out in the morning, right?)
     
  • Mi abuela prefiere tomar una siesta por la tarde. (My grandma prefers to take a nap in the afternoon.)

Topic 2: Using these 3 stem-changing verbs plus infinitive to express planning, wanting and preferring to do something.