a (prep.): at, to, per
a la una : one o’clock, at one o’clock
a qué hora : at what time
a tiempo : on time
adónde (adv.): where
ahora (adv.): now
almacén (n.): department store, warehouse
almorzar (v.): to eat lunch
almuerzo (n.): lunch
año (n.): year
anoche (adv.): last night

ayer (adv.): yesterday
baloncesto (n.): basketball
biblioteca (n.): library
cafetería (n.): cafeteria
casa (n.): home, house
cereal (n.): cereal
clase (n.): class
comer (v.): to eat
computador (n.): computer
conducir (v.): to drive
cuánto (adj.): how much,
                       how many

de (prep.): of (poss), about, from
desayunar (v.): to eat breakfast
desayuno (n.): breakfast
después (adv.): afterwards, later
después de (prep): after
devolver (v.): to return, to give back
dónde (interrog.): where
donde (adv.): where
dormir (v.): to sleep
dos : two
ejercicio (n.): exercise

el (art.): the (s., mas.)
en (prep.): in, at, on
escuela (n.): school
escuela secundaria (n.): secondary                school, high school
escribir (v.): to write
español (n., adj.): Spanish
esta, este (adj.): this
estudiar (v.): to study
fiesta (n.): party
fin (n.): end
fin de semana (n.): weekend

hacer (v.  irreg.): to do, to make
historia (n.): history
historia (n.): story
hora (n.): hour
hoy (adv.): today
infantil (adj.): children’s
ir (v.): to go
jugar (v.): to play [sport, game]
la (art.): the (sg., fem.)
las (art.):  the (pl., fem.)
libro (n.): book

los (art.): the (pl., masc.)
matemáticas (n.): mathematics
mes (n.): month
noche : night, evening
novio (n.): boyfriend
ocho : eight
pasado (adj.): last, past
película (n.): movie
playa (n.): beach
poder (v.): to be able to, 'can'
por (prep.): for, in (a time of day)

qué (interrog.): what
querer (v.): to want
química : chemistry
resolver (v.): to solve
sí (adv.): yes
tarde (n.): afternoon, early evening
tener (v.): to have
trabajar (v.): to work
traducir (v.): to translate
tres : three
todo (adj.): all

todos los días : everyday
un (adj.): a, an (s., masc.)
una (adj.): a, an (s., fem.)
universidad (n.): university, college
usted (pron.): you (formal, singular)
ustedes (pron.): you (formal, plural)
ver (v.): to see

'Z' changes to SOFT 'C' before 'I' and 'E';  Likewise: SOFT 'C' changes to 'Z' before 'A', 'O', 'U'
This does not affect any verbs in the present indicative tense, but affects many verbs in the first person form of the preterite past tense:
cruzar  yo cruzo (I cross); yo crucé, tú cruzaste (I crossed, you crossed)
almorzar  yo almuerzo (I eat lunch); yo almorcé, tú almorzaste (I ate lunch, you ate lunch)

HARD 'C' changes to 'QU' before 'I' and 'E';  Likewise, 'QU' changes to HARD 'C' before 'A', 'O', 'U'
This does not affect any verbs in the present indicative tense, but affects many verbs in the first person form of the preterite past tense:
sacar  yo saco (I take out); yo saqué, tú sacaste (I took out, you took out)
atacar  yo ataco (I attack); yo ataqué, tú atacaste (I attacked, you attacked)

SOFT 'G' changes to 'J' before 'A', 'O', 'U'
This affects the first person form of some verbs in the present indicative tense, but not in the preterite past:
escoger  yo escojo, tú escoges (I choose, you choose); yo escogí (I chose)
elegir  yo elijo, tú eliges (I elect, you elect); yo elegí  (I elected)

HARD 'G' changes to 'GU' before 'I' and 'E';  Likewise, 'GU' changes to HARD 'G' before 'A', 'O', 'U'
This affects the first person forms of some verbs in both the present indicative, and the preterite past tenses:
seguir  yo sigo, tú sigues (I follow, you follow); yo seguí (I followed)
pagar  yo pago (I pay); yo pagué, tú pagaste (I paid, you paid)

-AR and -ER verbs that had a stem-change in the present tense DO NOT change in the preterite.

-IR verbs that had a stem-change in the present tense DO have a change in the third-person singular and the third-person plural forms of the preterite.

These changes only affect the final vowels in the stem of the verb (just before the verb ending): 
e.g.  repetir (e-i,i) ==>  repitió
        preferir (e-ie,i) ==>  prefirió
The verb endings follow the normal patterns.