1. El imperfecto del subjuntivo con las cláusulas nominales
Past (Imperfect) subjunctive with noun clauses

2. What is this?
This is fancy grammar talk for a sentence with at least 2 clauses; the verb in the first (or main) clause determines whether or not the verb in the second (or dependent, subordinate etc.) clause is subjunctive.
If the verb in the first clause fits into any of several categories such as doubt, emotion, will/wish/want/desire, judgment/opinion, negation and several more (just deal with it), then the verb in the second clause is subjunctive.
Ejemplo:
I wanted you to learn.
Yo quería que aprendieras.
The second clause is called the noun clause because it functions like a noun; it is the object of the first verb (what you hope, wish, doubt etc.)

3. If the verb in the second clause has the same subject (yo, tú, ellos, Juan) as the verb in the first clause, you don’t use que and you don’t conjugate the second verb.
Ejemplo:
Juan wanted to learn
Juan quería aprender.

4. When do you use this?
Again, whenever you want to say that someone or something wanted or wished or hoped or doubted or didn’t believe or didn’t think or it was not possible or it was possible or etc. that someone or something else did or was something.

5. Or, look at it this way, with the help of 3 cutesy acronyms:
If the verb in the main clause falls into one these categories the second verb is subjunctive:
Necessity Judgment Wishes
Uncertainty Emotion Emotion
Desire Desire Desire
Emotion Influence Doubt
Impersonal expressions (“es necesario que…”)
Negation
God grant (“ojalá…”)

6. Examples “Ojalá vinieras a la fiesta.”
“Yo quería que Marcos me llamara.”
“Yo dudaba que salieras tan temprano.”
“Era posible que no me gustaran.”

7. What does a subjunctive verb mean in English?
Aprendiste = You learned
Aprendieras = You learned
Say what? Then how is it different?
Answer: it just feels different to a native speaker.

8. How do you conjugate the past subjunctive?
Put the verb in the ellos form of the preterit
Take off the –ron
Add these endings:
-ar / -er / -ir
-ra
-ramos
-ras
-ran

9. For some reason, these endings also exist (but seem to be less common)
-semos
-ses
-sen

10. The letter in front of –ramos always gets an accent
Ejemplo:
Le gustó que tocáramos bien.

11. There are no irregulars in the past subjunctive!!!!!!!!!!!!!!!!!!!!!!!*
*As long as you know all the preterit verb forms, you’ll do great

12. Conjugate and define these verbs in the past subjunctive, now, you!
Leer
Sentir
Dormir
Reírse
Zambullir
Estar
Ser
Decir

13. And if you’re the type of person that needs and can use this, here:
THESE WORDS ALWAYS INTRODUCE THE SUBJUNCTIVE
aconsejar que -to advise that
alegrarse de que -to be happy that
dejar que -to let/allow that
desear que -to wish that
dudar que -to doubt that
(me) emociona que -(I’m) excited that
(me) encanta que – (I) love that
(me) enfada que - (I’m) angry that
(me) enoja que – (I’m) angry that
esperar que - to hope that
estar orgulloso de que – to be proud that
exigir que -to demand that
(me) extraña que – It seems strange that
(me) gusta que – (I) like that

14. Más impedir (i) que -to impede insistir en que -to insist on
(me) irrita que – (I’m) irritated that
lamentar que - to lament that
mandar que -to order that
(me) molesta que – (I’m) bothered that
necesitar que -to need
negar que to deny that
ojalá que hopefully
oponerse a que -to oppose
pedir (i) que -to ask that
permitir que -to permit that
preferir (ie) que -to prefer that
prohibir que - to prohibit
querer (ie) que -to want
recomendar (ie) que to recommend that
rogar (ue) que -to beg that
sentir (ie) que – to regret that
(me) sorprende que – (I’m) surprised that
sugerir (ie) que -to suggest that
suplicar que -to beg that
temer que – to fear that
tener miedo de que – to be scared that

15. Y más THESE IMPERSONAL EXPRESSIONS ALWAYS INTRODUCE THE SUBJUNCITVE
es absurdo que it’s absurd that
es agradable que - it’s agreeable that
es bueno que - it’s good that
es dudoso que - it’s doubtful that
es escandaloso que - it’s scandalous that
es importante que - it’s important that
es imposible que - it’s impossible that
es improbable que - it’s improbable that
es indispensable que - it’s indispensable that
es inútil que - it’s useless that
es justo que - it’s right / just that
es malo que - it’s bad that
es mejor que - it’s better that
es necesario que - it’s necessary that
es peor que - it’s worse that
es posible que - it’s possible that
es probable que - it’s probable that
es raro que - it’s rare that
es ridículo que - it’s ridiculous that
es sorprendente que - it’s surprising that
es triste que - it’s sad that
es una lástima que - it’s a shame that
es útil que - it’s useful that
más vale que - it’s better that
no es que - it’s not that
no es cierto que - it’s not certain that
no es evidente que - it’s not evident that
no es obvio que - it’s not obvious that
no es verdad que - it’s not true that
ojalá que - hopefully

16. Not subjunctive THESE WORDS ALWAYS INTRODUCE THE INDICATIVE
aprender que -to learn that
comprender que -to understand that
creer que -to believe that
darse cuenta de que -to realize that
entender que -to understand that
estar cierto que -to be certain that
estar seguro que -to be sure that
oír que -to hear that
opinar que -to think (opine) that
parecer que -to seem that
pensar que - to think that
saber que -to know that
ver que -to see that