We started to think of a few and he wondered why these mistakes kept cropping up in his wife's fluent Spanish no matter how many times they'd been corrected. In language teaching we usually call them fossilized errors.
One of these is the use of the verbs ACORDARSE y RECORDAR. It's very common to hear a non-native Spanish speaker say no me recuerdo instead of no me acuerdo, and we just can't understand why.
ACORDARSE means ¨remember something which we may forget or have forgotten¨, so I should say:
No me acuerdo. I don´t remember.
Acuérdate de llamarlo. Remember to call him.
(Notice the use of to+infinitive when we refer to something that needs to be done).
Siempre me acordaré de ti. ¨I will always remember you.¨
Acordarse is a pronominal verb, i.e. we need to use the pronouns ¨me, te, se, nos, os¨ when using it.
RECORDAR means ¨recall¨ with the idea of bringing back to your mind something that happened in the past:
Recuerdo cuando fuimos a visitarlo. I remember visiting him.
(Notice the use of -ing after remember when we refer to something that has already happened).
Siempre lo recordaré. I will always remember/recall it.
It can also mean ¨remind¨:
Recuérdame que le llame mañana. Remind me to call him tomorrow.
Me recuerda a mi padre. He reminds me of my father.
ACORDAR this verb isn´t pronominal and it means ¨to agree¨:
Acordamos vernos a las 4 en punto. We agreed to meet at 4 o'clock sharp.