The Präsens and Präteritum are the two "fully conjugated" forms in German (that is, they don't use an auxiliary verb), so it's good to learn them together. Here’s the weak verb kaufen (to buy):

Notice the pattern: the "en" ending of the infinitive is removed (sometimes it’s just an "n") and replaced with the appropriate highlighted ending. The past tense endings are mostly just the present tense endings with an extra t; this is the “weak” past tense ending mentioned in V.I, and it’s directly related to the –d ending in the weak English past tense.

These twelve endings are used for every weak verb in German, without exception. Some of them are hard to pronounce if the verb has certain consonants at the end of the stem; in this case an e is added in between the stem and the ending. For example, here is the weak verb reden (to talk). Notice how without the extra e it would be harder to distinguish among these forms:

Also notice that the Sie form, the formal second person that we learned about in Section 4, is conjugated exactly the same as the third person plural (“they”). This is true for all tenses and moods, and for all types of verbs.

Strong verbs are a little different. Remember that strong verbs form their past tense with a vowel shift rather than an added t; some of them also have a (different) vowel shift in the present tense, but only in the 2^nd and 3^rd person singular. There’s no one rule for these vowel shifts -- you have to learn them when you learn the verb, just as you once learned to say "broke" instead of "breaked" in English. Here’s the strong verb fallen (to fall):

Notice that the present tense endings are the same as for weak verbs. Also notice that with both strong and weak verbs, the 1^st and 3^rd person singular are the same in the past tense, and the 1^st and 3^rd person plural (we and they) are the same in both tenses.

Now let’s try a mixed verb. Remember that there are only a few of these, and they combine the strong past stem changes with the weak past endings. Mixed verbs do not have the strong vowel shift in the present tense, except for wissen (which becomes weiß). Here is bringen (to bring):

Modal verbs are irregular in the present singular tenses, and weak in the plural:

You may have guessed that the English modal verbs can and must are directly related to these forms. So is will, but be careful, because the way we use it in modern English translates to werden rather than wollen. Ich werde es tun means I will do it, while Ich will es tun means I want to do it.

The modal verbs have weak endings in the past tense, but they lose their umlauts and mögen has a stem change:

Finally, the three auxiliary verbs are almost completely irregular, especially sein: