Ob - Ol
| Last Name | First and Middle | Township | School Name or # | Years | Living? Yes, No | Spouse | Living? Yes,No |
| Obanion | Dorothy | Plymouth | 4 | 1936-1937 | no | Hathaway | |
| Obanion | Dorothy | Washington | 5 | 1939-1940 | no | Hathaway | |
| Obanion | Laura Mae | Grant | 6 | 1933-1934 | no | Johnson | |
| Obanion | Laura Mae | Liberty | 1 | 1934-1936 | no | Johnson | |
| O'Boyle | Bess | Hancock | 1 | 1920-1922 | |||
| O'Brien | Adelade | Elkhorn | 8 | 1915-1916 | |||
| O'Brien | Adelade | Elgin | 2 | 1916-1917 | |||
| O'Brien | Adelade | Plymouth | 5 | 1917-1918 | |||
| O'Brien | Adelade | Elkhorn | 8 | 1918-1919 | |||
| O'Brien | Mary L. | Johnson | 5 | 1915-1916 | |||
| O'Brien | Mary V. | Liberty | 9 | 1915-1916 | |||
| O'Brien | Mary V. | Liberty | 3 | 1916-1918 | |||
| O'Bryan | Mary O. | Perry | 8 | 1915-1916 | |||
| O'Connell | Loretta Kettler | Perry | 3 | 1940-1941 | |||
| O'Connell | Loretta Kettler | Stanton | 5 | 1943-1944 | |||
| O'Conner | Helen | Liberty | 9 | 1921-1922 | |||
| O'Connor | Helen | Stanton | 8 | 1917-1918 | |||
| O'Connor | Helen | Grant | 4 | 1918-1918 | |||
| O'Connor | Helen | Hungerford | 6 | 1918-1919 | |||
| Oehlerling | Marilyn | Union | Cons'd | 1956-1957 | |||
| Oelson | Luella Van Buskirk | Elkhorn | 8 | 1952-1954 | |||
| Oetken | Kathleen Doherty | Union | Cons'd | 1949-1951 | |||
| Offerman | Hildegard | Remsen | 2 | 1921-1922 | |||
| Offerman | Hilregard | Henry | 3 | 1922-1926 | |||
| Ogden | Bartley | Westfield | 2 | 1925-1926 | |||
| Ogden | Bartley | Grant | Craig | 1926-1927 | |||
| Ogden | Gladys | Westfield | 3 | 1928-1929 | |||
| Ogden | Gladys | Johnson | 6 | 1929-1930 | |||
| Ogden | Oma | Westfield | 4 | 1925-1926 | |||
| Ogden | Oma | Portland | Searls | 1926-1927 | |||
| Ogden | Oma | Sioux | 5 | 1927-1928 | |||
| Ogren | Ruth | Hancock | 4 | 1915-1917 | |||
| Ohlendorf | Amilda | Remsen | 5 | 1928-1929 | |||
| Ohlendorf | Clara | Remsen | 3 | 1915-1917 | |||
| Ohlendorf | Clara | Meadow | 3 | 1917-1918 | |||
| Ohlendorf | Lucy | Meadow | 9 | 1926-1927 | |||
| Ohlendorf | Lucy A. | Meadow | 8 | 1920-1925 | |||
| Ohlrichs | Bernice | Johnson | 5 | 1944-1946 | |||
| Ohlrichs | Bernice | Johnson | 4 | 1946-1949 | |||
| Ohm | Gertrude | Union | Cons'd | 1955-1956 | |||
| Ohm | Gordon E. | Union | Cons'd | 1953-1956 | |||
| Okerstrom | Ruth | Washington | 4 | 1939-1940 | |||
| Okerstrom | Ruth | Preston | 6 | 1940-1942 | |||
| O'Leary | Kitty | Garfield | 2 | 1896-1896 | |||
| O'Leary | Marian | Garfield | 2 | 1892-1892 | |||
| Oleson | Irene E. | Henry | 8 | 1938-1942 | |||
| Oleson | Luella Van Buskirk | Elkhorn | 4 | 1945-1947 | |||
| Oleson | Luella Van Buskirk | Henry | 5 | 1947-1950 | |||
| Oleson | Luella Van Buskirk | Henry | 6 | 1950-1952 | |||
| Oleson | Merle | Henry | 8 | 1936-1937 | |||
| Oliver | Donnabelle | Liberty | Cons'd | 1956-1957 | |||
| Ollendick | Catherine | Lincoln | 4 | 1945-1946 | |||
| Oloff | Esther | Grant | Craig | 1954-1962 | |||
| Oloff | Esther | Liberty | Cons'd | 1954-1962 | |||
| Oloff | Esther Winterfeld | Preston | 7 | 1951-1954 | |||
| Olson | Doris V. | Plymouth | 5 | 1920-1921 | |||
| Olson | Edna M. | Preston | 4 | 1934-1936 | |||
| Olson | Edna M. | Portland | Searls | 1936-1938 | |||
| Olson | Luella | Garfield | 4 | 1920-1921 | |||
| Olson | Thomas D. | Union | Cons'd | 1948-1953 | |||
| Oltmanns | Deloris | Grant | Craig | 1946-1947 |
