Los Verbos Cambiantes

Explanation:
In all three conjugations of verbs the ar, er, and ir there are some verbs whose vowels change in the middle. These types of verbs are called stem-changers. They occur in all pronouns except nosotros and vosotros (which you do not need to know if you don’t live in spain). These two pronoun views maintain the regular stem. There are six varieties of stem-change. For example;

o changes to ue           e goes to ie            e to i               i to ie            u to ue

One of the main reasons for the use of stem changing verbs is because the sound of the word. In order to make a verb/word easier to say, they altered the middle of it. Also they do this in order to make words not sound like, or look like another words. Although stem changing verbs do not exist in the english language something that is similar to this is how 2 or more letters together can make a different sound than what it would normally make if they were separated. For example the way that TYP changes its sound in order to be easier to say. Such as the word TYPE and the word TYPICAL. Another example is the words CHURCH and CHRISTMAS. Some examples in spanish are; instead of saying podo, you say puedo.

HISTORY

Among the -ar and -er verbs, the modern e ~ ie and o ~ue alternations that are exhibited in the present tense directly reflect (in principle at least) the diphthongization of Vulgar Latin. The latter sounds, because they occurred only in stressed syllables, appeared as root vowels only in the rhizotonic forms of the paradigm. This situation is reflected in modern Spanish in the fact that the diphthongs ie and ue occur in the rhizotonic forms of the present tense, whereas the corresponding monophthongs e and o occur in the forms in which the stress falls on the ending. This is illustrated below:

The root vocalism of -ir verbs has a rather more complex history than that of the -ar and -er verbs. Here the crucial factor was metaphony, induced by the root increment j that was present at various points in the relevant verbal paradigms. This j was the reflex of an earlier full vowel, either i or e, which semi vocalized following the generalized loss of the hiatus.

Spanish is ultimately a derivative of Latin. Classical Latin as we know it is a rather artificial, formal, and archaic version of what was actually spoken in the days of the Roman Empire. This kind of Latin ceased to be in colloquial use sometime around the second century BC, but its use in oration and especially writing has continued down to the present day. But the language spoken by the common man, and promulgated by the advancing Roman legions, was vulgar Latin (not so called because it used naughty words, but because it was spoken by the vulgus). As nearly always happens with living languages, the vulgar Latin diverged greatly over time from classical Latin, which remained essentially intact, and became a base corruption of its former self (though in truth, all natural languages are corruptions of their former selves).

http://www.university-world.com/spanish/spanish_history.html

The Linguistics of Spanish

https://www.staff.ncl.ac.uk/i.e.mackenzie/hisverb.ht

 

How to use stem changes

https://m.youtube.com/watch?v=sDaDoL9IYso

 

Real Life Examples

• “Yo quiero la pluma rojo.”
• “I want the red pen.”

• “Tú piensas la camisa costar quince euros.”
• “You think the shirt cost 15 euros.”

• “Shrek prefiere las manzanas.”
• “Shrek prefers apples.”

• “Carlos cierra la ventana.”
• “Carlos closed the window.”

• “Los estudiantes entienden mathematica y ciencias.”
• “The students understand math and science.”

• “Yo empiezo la examan.”

• “I began the test.”

• “Yo quiero ir de compras a el centro comercial para los jeans.”
• “I want to go shopping at the mall/ shopping center for jeans.”

• “Los estudiantes entienden números.”
• “The students understand numbers.”

• “Tu empiezas la carrera rapido.”
• “You begin the race fast.”