What must be part of a quantitative observation?

A quantitative observation must be a measurement of some sort. (Something including numbers). Qualitative, on the other hand, is when you are using words to describe what has happened.

Explanation:

Quantitative observations are performed with devices such as rulers, balances, measured cylinders, beakers, and regulators. These results are measurable,using one or more senses to gather knowledge. information that doesn't involve numbers or measures. the process of making an understanding based on observations and previous knowledge. Quantitative investigations always involve numbers.

a chemical reaction

explanation: