ich stellte fest, dass

I found out that

→ ich
phrase Rare #42,958
I found out that This is the simple past form of „feststellen“ and is used to report a discovery, observation, or realization. Depending on context, it can also mean “I noticed that” or “I realized that.”
GE: Ich stellte fest, dass ich meinen Schlüssel zu Hause vergessen hatte.
EN: I realized that I had forgotten my key at home.

Ich stellte fest, dass ihr die Lösung dieses Problems schwer fiel.

I noticed that she was having difficulty solving this problem.

Ich stellte fest, dass die Schachtel leer war.

I noticed that the box was empty.

Ich stellte fest, dass mein Fahrrad verschwunden war.

I noticed that my bike was missing.

Ich stellte fest, dass die Maschine nutzlos war.

I found the machine useless.