Many German verbs are built from a prefix + a base verb, and in a normal statement the prefix splits off and moves to the very end of the sentence. It looks strange in isolation and becomes intuitive with repetition.
Take einkaufen (to shop) - built from prefix ein- + kaufen (to buy). Conjugate the base verb normally (Lesson 3's pattern), and send the prefix to the end:
Ich kaufe heute ein. (I'm shopping today.)
Ich rufe den Arzt an. (I'm calling the doctor. - anrufen)
Ich stehe um sieben auf. (I get up at seven. - aufstehen)
The infinitive form (as listed in a dictionary) always keeps the prefix attached at the front: einkaufen, anrufen, aufstehen. It only splits when the verb is actually conjugated in a normal statement or question.
| einkaufen | to shop |
| anrufen | to call (phone) |
| aufstehen | to get up |
| fernsehen | to watch TV |
| mitkommen | to come along |
| anfangen | to begin |
When a separable verb appears after a modal verb (Lesson 11), it stays whole at the end, since the infinitive already occupies that slot:
Ich möchte heute einkaufen. (no splitting - the infinitive form stays intact)
A second group of prefixes never splits: be-, ge-, er-, ver-, zer-, ent-, emp-, miss-. Verbs like verstehen (to understand), bekommen (to receive), and empfehlen (to recommend) stay whole in every tense, and skip ge- entirely in the Perfekt participle (verstanden, not "geverstanden"). See Lesson 72 for the full explanation.
Cross-checked against the Goethe-Institut A1 practice materials.