The improvement in his grades pleases his parents.
Wir haben eine Verbesserung der Lage bemerkt.
We noticed an improvement in the situation.
Der Arzt erwartet bald eine Verbesserung.
The doctor expects an improvement soon.
Note
The article is part of the word: die Verbesserung. That way you learn the gender with it.
Remember die Verbesserung for good. ripiti brings the word back just before you forget it, with these sentences. Free, no account needed, works offline.