What is Happening:  We don’t know anything about what happens earlier in the day other than Jesus is focusing on the Passover Meal (start reading at Matthew 26:17).  At some point his disciples come to him and ask where he would like to eat the Passover Meal.  According to Wikipedia, the Passover Meal is:

“The Passover Seder (Hebrew: סֵדֶר‎ [ˈsedeʁ], “order, arrangement”; Yiddish: Seyder) … a Jewish ritual feast that marks the beginning of the Jewish holiday of Passover. It is conducted on the evenings of the 14th day of Nisan in the Hebrew calendar, and on the 15th by traditionally observant Jews living outside Israel. This corresponds to late March or April in the Gregorian calendar.

The Seder is a ritual performed by a community or by multiple generations of a family, involving a retelling of the story of the liberation of the Israelites from slavery in ancient…