observation diary; observation journal
A diary or journal for recording observations, commonly used in educational contexts such as nature observation, plant growth, or weather records. Often appears as a suffix in compound titles like 植物観察日記.
For summer homework, I kept a morning glory observation diary.
The teacher records the weather and temperature in an observation diary every day.
日記 is a general diary or journal, while 観察日記 specifically focuses on recording observations, often for educational or scientific purposes.
観察記録 is a more formal term for observation records, often used in research or official documentation, whereas 観察日記 implies a daily, personal, or educational log.
Compound of 観察 (kansatsu, 'observation') and 日記 (nikki, 'diary'). The reading にっき is a standard rendaku form of 日記.