Do you remember that there are some irregular verbs? Unregelmäßig?
Yes, how could I forget?
Well, don't worry, practice makes perfect. They follow a pattern:
essen
ich
esse
du
isst
er/sie/es
isst
wir
essen
ihr
esst
Sie/sie
essen
Oh, ich sehe! It's like with sehen, where du and er/sie/es change a bit, right?
Exactly!