1. BOOT VERBS In the present tense
Stem-changing verbs
BOOT VERBS
In the present tense

2. HOW do you find the stem? Drop the –ar, -er, or -ir ending
The remaining portion of the word is called the stem:
Example: Querer without the –er verb ending is Quer; therefore, Quer is the stem of the verb Querer.

3. WHEN does the stem change?
Stems only change in the yo, tú, él/ella/usted, & ellos/ellas/ustedes forms.
Stems DO NOT CHANGE in the nosotros and vosotros forms, which is why stem changers are often called boot verbs.

4. HOW does the stem change?
1. When dealing with stem-changing verbs in the present tense, only stem vowels can change.
The vowels that change are o, u or e (not a or i).
2. The four types of present tense stem-changers are:
o->ue dormir, llover, etc.
e->ie querer, nevar, etc.
u->ue jugar
e->i servir, pedir, etc.

5. WHERE does the stem change?
The vowel closest to the end of the word is the letter that changes. It is easy to identify the changing vowel in short words such as dormir (1 vowel in the stem), but it can get more complicated with longer words such as querer (2 vowels in the stem):
Quererdrop –er verb ending  Quer vowel closest to the end of the word changes: Quer 
Quiero
Quieres
Quiere
Quieren

6. Quiero
Queremos
Quieres
Queréis
Quiere
Quieren

7. Weather
Two important “boot verbs” to know are: llover (o→ue) – to rain
& nevar (e →ie) – to snow