noun
exercise book; workbook; practice notebook
A notebook or book used for practicing skills, such as writing, math, or music. Often used in educational contexts.
漢字の練習帳を買った。
I bought a kanji practice notebook.
ピアノの練習帳に毎日取り
I work on my piano workbook every day.
問題集 is a collection of problems or questions for practice, often used for test preparation, while 練習帳 emphasizes repetitive skill-building exercises.
Compound of 練習 (practice) and 帳 (notebook, register). The exact historical derivation is uncertain, but the word transparently means 'practice notebook'.