There are many methods by which scientists make observations. Three of these methods are controlled experiments, natural experiments, and models. Match each description of a procedure to the correct category of observation.

Drag each item on the left to its matching item on the right.

Scientists grow coral in labs and subject some to changes in water chemistry.

Public health researchers study the hospitalization rates for asthma before and after a city limits vehicle traffic.

Scientists develop a computer program that simulates the effects of changing temperature, $pH,$ and other variables on coral.

The world's most powerful supercomputers are updated moment to moment with new observations of weather conditions to generate a forecast.