Step 2: How do chains break?
The most common way is by pedaling full force at the same moment that you are shifting your front derailleur. Other breaks I've seen were caused by an assortment of seemingly one-in-a-million occurrences, yet i've seen enough of those cases that i guess if you ride long enough one-in-a-million still happens. Things like a nail getting thrown up by my front wheel and lodging in the chain, then getting cranked across the sprocket. who'd a thunk?