noun
backpack
A2
Rucksack (der Rucksack): masculine noun meaning 'backpack' or rucksack. Plural: Rucksäcke (umlaut + -e). Genitive singular often des Rucksacks. Dative plural den Rucksäcken (adds -n). Regular noun with plural stem change (a -> ä) in plural. Remember the article der in nominative singular.
Examples
Die Schüler stellten ihre Rucksäcke in die Ecke, bevor die Lehrerin den Unterricht begann.
The students put their backpacks in the corner before the teacher began the lesson.
Ich packe mein Buch in den Rucksack.
I'm putting my book into my backpack.
Ich packe meinen Rucksack.
I'm packing my backpack.
Details
Mnemonics
Picture a student with a big backpack labeled 'der Rucksack' on the straps.
Ruck-sack — imagine a bag that gives you a small 'ruck' when you pick it up.
der Rucksack — masculine: imagine a strong (der) hiker carrying it.