
Combustion
Visual Imagery
 Imagine the visible aspects of burning to associate with 'combustion', like flames and smoke. 
The campfire's combustion filled the night with orange light.
 Spontaneous Danger
 Understand 'spontaneous combustion' can refer to unexpected, sometimes dangerous events. 
The warehouse suffered from spontaneous combustion due to chemical storage.
 Non-Literal Use
 Recognize when 'combustion' is used metaphorically to express vigorous activity or emotions. 
The crowd's excitement reached a level of combustion when the band appeared.