のに

1. Origins, structure, and basic meaning

• Structure: Nominalize a dictionary-form verb with の and add に to express a use or requirement.
• Basic usage: このはさみは厚い紙を切るのに便利だ。 evaluates the scissors as convenient for cutting paper.

2. Common pitfalls and similar expressions

• Use and contrast
  • 切るのに便利だ evaluates a cutting use, while 切ったのに使わなかった contrasts cutting something with not using it afterward. Following expressions of convenience, necessity, or required resources help identify the use meaning.
• Time required
  • 作るのに一時間かかる states the time needed to make something. It differs from connecting an action to its goal, as in 作るために早く起きる.