What is the difference between 'will' & 'shall' ?
"Will" is used to predict future actions, or with voluntary actions/promises.
He will be ready by nine.
I will clear up once we finish dinner.
"Shall" is used to indicate future action or suggestions. "Shall" is also used with voluntary actions/actions. In formal English, the use of "shall" to describe future events implies inevitability.
Shall we leave now?
I shall visit Grandma yesterday.
The most fundamental difference between the two is that "shall" is used primarily with "I" and "we". Also, "shall" indicates a finality, e.g.
You shall not go to school tomorrow.
In the above example "will" does not carry the same 'weight' as shall does.
But then again, that's how I understand it, and I'm not a teacher
You'll find more examples and explanations
here and
here.