El pasado irregular   The irregular past tense

 I did / made  
 hice  we did / made  
 you did / made (informal)   
 you did / made (formal) 
 y'all did / made (informal) 
 y'all did / made (formal)  
 he did / made  
 she did / made 
 it did / made   

 they did / made  


 I was (somewhere)  
 estuve  we were (somewhere)  
 you were (somewhere) (informal)   
 you were (somewhere) (formal) 
 y'all were (somewhere) (informal) 
 y'all were (somewhere) (formal)  
 he was (somewhere)  
 she was (somewhere) 
 it was (somewhere)   

 they were (somewhere)  


¿Qué hiciste ayer?  ¿Qué hiciste el fin de semana pasado? ¿Qué hiciste en las vacaciones?

Notice that when you ask about what a friend did yesterday, last weekend, and last summer, you use the verb hacer, which has an irrregular spelling in the past tense.

Several verbs have irregular spellings in the past tense.  What that means is that the stem of the verb (the part that usually does not change) has a different spelling than the original verb.  With hacer, it means that the hac- at the beginning changes to hic-.  

Notice that hacer and estar, above, use exactly the same endings, even though hacer is an -er verb, and estar is an -ar verb.
Almost all irregular verbs use the same 6 endings.  It doesn't matter if they are -ar, -er, or -ir verbs, they all use the endings below.  

Mira la lista de verbos irregulares en el pasado:

preterite stem  español  inglés
 anduv-  andar  to walk, to go
 estuv-  estar  to be somewhere, to be in a momentary state
 hic-  hacer  to make, to do
 pud-  poder  to be able to, can
 pus-  poner  to put 
 quis-  querer  to want (something) or to love (someone)
 sup-  saber  to know (in preterite means found out)
 tuv-  tener  to have (in preterite means got)
 vin-  venir  to come

There are three verbs that follow their own rules: ser, ir and dar.  The conjugations of each of these verbs is below.