Conjugation of Verbs

German verbs are subdivided into so-called strong and weak verbs. The strong verbs change in root as compared to the infinitive, the weak verbs don't. Both groups of verbs, however, in principle share the same endings. Cf. for example:

The weak verb machen (= to do, to make):
ich mache
du machst
er, sie, es macht
wir machen
ihr macht
sie machen

The strong verb sprechen takes the same endings, but the vowel of its root changes in the second and third person singular:
ich spreche
du sprichst
er, sie, es spricht
wir sprechen
ihr sprecht
sie sprechen

Knowing this regularity (in all its irregularity), which is valid for most - though not all - strong and weak verbs, makes the learning of German verb patterns a lot easier.

This statement is all the truer as the same regularity applies to the German Past Tense (Präteritum). Cf. machen (as a weak verb):
ich machte
du machtest
er, sie es machte
wir machten
ihr machtet
sie machten

and sprechen (as a strong verb):
ich sprach (= zero ending)
du sprachst
er, sie es sprach (= zero ending)
wir sprachen
ihr spracht
sie sprachen

(Note: In the strong verbs, the forms for ich and er, sie, es mostly do not have any ending and are identical.)