left to right as identified on back of the picture
back row 
Art Boedecker
Otto Boedecker
Albert Boedecker
Albert Marten
Carl Boedecker
Paul Boedecker

middle row
Miriam Opperman Grauman
Norma Boedecker
Irma Marten Kuhfus Dannenberg
Lydia Neuhaus Marten
Ruth Boedecker holding Friedrich
"Grandma" Henrietta Siekmeier Marten
Lydia Opperman
Laura Boedecker

front row
Daniel Opperman
Ralph Opperman
Hilda Marten Reineking
Francis Boedecker
Helen Opperman

The occasion was "Grandma's" birthday, June 23, 1924
Grandma Marten died May 3, 1925

Note that "Grandma" Marten is an original immigrant
from Germany. She was born in 1842 in Germany.

The place of the picture is believed to be the Marten farm.