Grammar 8.2: Preterite of -IR verbs that stem change in the present tense

Your book is so frustrating. Instead of just focusing on the preterite of -IR verbs with present-tense stem changes, it instead insists on talking about the preterite of all families of verbs that stem change in the present tense.

• This is an absolute waste of time.
• As we have already seen, -AR verbs that stem change in the present tense and -ER verbs that stem change in the present tense do not ever show stem changes in the preterite.
• Period.
• No more needs to be said.

But let's repeat it one more time, just for those who might not be paying attention:

• It doesn't matter if -AR and -ER verbs stem change in the present tense.
   
• They will not show a stem change in the preterite.

For -IR verbs, though, it does matter if they stem change in the present tense.

Let me give you the good news first:

• Most of the time, -IR verbs with present-tense stem changes act as you'd expect them to in the preterite.
   
• When the subject is yo, tú or nosotros, nothing happens to the stem at all. Seriously, not a thing:

However...

When the subject is 3rd-person (whether 3rd-person singular or 3rd-person plural):

• There will be a SIMPLIFIED, single-vowel preterite stem change.
• If the verb stem-changes o-ue in the present, it will make an o to u stem change in the preterite.
• If the verb stem-changes e-ie or e-i in the present, it will make an e to i stem change in the preterite.

Let's look at this all together.

Remember:

• When the subject is yo, tú or nosotros, nothing happens to the stem at all.
• We only make a simplified preterite stem change when the subject is 3rd-person singular or 3rd-person plural.

The preterite of -IR verbs that stem change in the present tense is very important, and it will be prominently featured in both the upcoming Preterite Quiz and the Final Exam.

• What is not important, and what will not be part of those two tests, is the material in Grammar 8.3--verbs that change meaning in the preterite.

For your own knowledge, it's nice to be aware that:

• "conocí" means "I met" (not "I knew"),
• "pude" means "I managed to" (not "I could/was able to"),
• "supe" means "I found out" (not "I knew"),
• "quise" means "I tried to" (not "I wanted to").

But you are not expected to master this.

Just focus on Grammar 8.2, please.