Preterite of regular verbs: Grammar guide

A simple conjugation of an -ar verb in the preterite would look like this:

(1) Notice also that verbs that would normally have stem changes in the present (o-->ue or i-->ie) do not change in the past tense in the same way. There are other changes that we will talk about later for irregular verbs. So, in the present, the ella form is encuentra, while the ella form in preterite is encontró