"¿Dormimos en tu cama o en mi cama?"
Translation:Do we sleep in your bed or in my bed?
So why exactly is, "Will we sleep in your bed or my bed?' a wrong answer when, "Shall we sleep in your bed or my bed?" is acceptable?
Edit: three years later, I turn to Google for insight. From Oxford dictionaries: The traditional rule is that shall is used with first person pronouns (i.e. I and we) to form the future tense, while will is used with second and third person forms (i.e. you, he, she, it, they). For example: I shall be late.
'Shall' only is correct, for the simple future. The correct convention is that, for the simple future 'shall' is used for first person singular and plural; 'will' being used for the other persons. For the emphatic (or 'coloured' [Fowler]) future, the usage is reversed. "I will do it" meaning, "I will that it be done".