くする

1. Origins, structure, and basic meaning

• Structure: Change an i-adjective's final い to く, then add する.
• Basic usage: 音を少し小さくした。 means reducing the volume a little.

2. Common pitfalls and similar expressions

• The affected object and the change itself
  • 音を小さくする describes acting to change the sound, while 音が小さくなる describes the sound becoming quieter. を marks the affected object and が the subject of the change.
• Adjective class and inflection
  • 大きくする uses an i-adjective, while 静かにする uses a na-adjective. Tense or a request appears in the final する part, as in 小さくした and 小さくしてください.