“Easter” is the period of eight Sundays [until Pentecost], comprising fifty days, often called as a unit “the Great Fifty Days” . . . . For the explosive force of the resurrection of the Lord is too vast to be contained within a celebration of one day. . . .
The recovery of Easter as “the Great Fifty Days” of the year can move the church along toward a fuller understanding of what the resurrection of its Lord implies. Easter is not one closing day at the end of a lengthy period of Lent. Easter is one extended rejoicing in the resurrection that more than exceeds in length the Lenten disciplines. The first day of the season, Easter Day, is the opening of a protracted celebration, even as the Resurrection is itself the opening to a vast new reality. . . .
“The First Sunday After Easter” implies Easier is over, having lasted only one day. But “the Second Sunday of Easter” (for the same date) indicates that Easter is an extended season, whose essential character is shared by all of its parts. The careful use of “Easter Day” rather than “Easter” for the opening occasion further presses this point.
Once Easter is seen as a season, congregations can work at distinctive worship practices throughout the Great Fifty Days in order to tie the weeks together more clearly in the hearts of worshipers. For example, on Sundays Two through Seven, one stanza of a hymn used on Easter Day might be sung as an acclamation (“Christ the Lord Is Risen Today” is one possibility).
—Laurence H. Stookey, Calendar: Christ’s Time for the Church, 54, 56-7 (***Highly recommended reading!)