| A | B | 
| flammable | able to burn | 
| humanity | human kind | 
| ignition | the place where something starts | 
| flame | the flickering part of a fire | 
| precise | accurate, exact | 
| precision | an exact or accurate state | 
| meter | a measurement or measuring device | 
| metric | describes a system used to measure | 
| microscope | a tool use to look at tiny organisms | 
| microscopic | describes something that is too tiny to see with the naked eye | 
| grave | describes something that is serious | 
| gravity | seriousness | 
| grateful | thankful | 
| gratitude | the state of being appreciative | 
| revise | to change | 
| revision | a change | 
| athlete | someone who plays sports | 
| athletic | describes someone or something that has to do with sports | 
| humane | kind and compassionate | 
| ignite | to start or begin something |