What are two examples of observations you might make, and two examples of inferences you might make, when looking at logs burning in a campfire?

One observation would be the change in odor when observing the logs burning in a campfire and because of that a inference could be because a change in odor is occurring, a chemical change is happening to the logs (combustion).

A second observation would be that the wood being burned gave off smoke at first but then stopped and because of that a inference would be that the compound that were being burned creating the smoke was all evaporated from the wood.