Max’s ABC by Rosemary Wells.
The beloved bunny siblings Max and Ruby return in an alphabet book.  Nicely, the book can be read as an alphabet book or simply as a story.  Max’s ants escape from their ant farm and climb up on him to get his cake.  When Max tries to get them off him by pouring juice on himself, Ruby has to come to the rescue.  The story is silly and filled with the simple fun you expect in a Max and Ruby book.  This one is a gem worth sharing on that first day of an alphabet unit.