1884 - Anna Myrtle Saunders taught a six month term of school beginning in September and lasting until March in a sod house. This was ungraded school sessions. Subjects taught were Reading, Spelling, Penmanship, Arthithmetic, Geography, U.S. History, Civil Government, Grammar, Physiology, Calisthenics and Music. This first sod house school in Arnold was at Carol Watson’s current home.
1885- Miss Ella Kinney taught the second term of school in the sod Methodist Church. Mr. Walker finished the term.
1886 - Amy Robertson taught in the church
1887 —A small frame building especially for school, was put on on a lot donated east of the Baptist church.
1889- a Second room was added to accommodate the 50 plus students.
1896 - Mrs. B. V. McKenny taught
1900-1901 - Mrs. B. V. McKenny resumed teaching
1904 - Kate Walsh
1905 - George Gordon, Gertie Allen, Blanche McGuire and Pearl Hunter were teachers.
1905 - The school building became overcrowded so school was held in John Mead's Harness Shop with lower grades on the lower floor and the upper grades on the second floor.
1906 - The first year in the new framed building with a belfry.
1908-1909 - Professor McKee faced discipline problems in the upper grades, left, and was replaced by the preacher's wife Mrs. Eaton. She was then replaced by Professor Claude Pickett. He stayed for 8 years.
1909 - Marked the beginning of Arnold High School
1909 - E.C. Pickett hired as principal
1910 - On January 15th, the Broken Bow Courthouse burned, losing most rural school records.
1910—Grade 10 was added to the high school. Then the two other grades were added.
1911—Evidence that overcrowding was a problem for the school. They used the Evergreen sod house school and they were taught by Amy Robertson. They also knew the railroad was coming, so they planned for a new building.
1911 - with no 11th or 12 grade classes graduation was held for those in the 10th grade.
1913—The building was sold to Sylvester Tubbs; The first four-year class graduates.
1913 - The first 4-year high school graduates received their diplomas.
1914- March, the cornerstone of the brick school building was laid, even though there was a shortage of iron, and it delayed progress.
1914—The frame structure building was replaced with a new brick building. The Old Elementary School by the old Baptist church, originally built for both elementary and high school classes, was built by M.L. Henderson.
1916 - Wilbur Gettys was sticken with heart failure and died before he could be taken from the football field. (The team had left home to play a game against Mason City Friday, and Ansley on Saturday.) They put a "quietus on football in Arnold for the rest of the season."
1918—Last year that classes were allowed to graduate in three years.
1919—No graduating class due to requirement changes.
1920 - U.S. Dunn hired as superintendent
1921- Emil Benthack hired as superintendent.
1921- The first yearbook (in four volumes) was published.
1923 - Work on the new high school began on land just south of Will Mills' residence. (There was no gymnasium, so basketball games were played in the Rex Theater and the basement of the Baptist Church.
1924 - State Runners Up in Class M of basketball tournament.
1925 - Dedicated in October. The move to the new building happened in November and the 1925-1926 term finished there. Emil Benthack, superintendent; C.H. Hare, principal; Frank Allen, agriculture; Marta Rankin, music; Olga Brecks; Mable Landon; and Lillian Curyea for other subjects.
1930 - C.H. Hare hired as superintendent
1932-1933 - Arnold school faculty took a reduction in salary two years in a row to ensure were rehired. It was 1936 before they received a raise in pay again.
1943 and 1944 - no yearbooks were produced during the war years.
1944 - Lee Hirsch hired as superintendent
1946 - Harry Lenhouts hired as superintendent
1947 - Football resumes for the first time in 30 years.
1950s - seventeen adjoining rural districts consolidated with Arnold.
1952 - Jack Welch hired as superintendent.
1958 - Alvin Story hired as superintendent.
1958 - Class C Football Champions
1960—The Hot Lunch program began.
1961 - The cornerstone of the building was laid in November.
1962 - May dedication services. The students helped do some of the moving from the old elementary into the new classrooms by walking their desks and books up to the new location.
1962 - the last year of use of the brick elementary school building
1963—Classes were held in the new elementary section added to the existing high school building.
1964—The old brick elementary school building was torn down and the house that was built in place of it, is still there today.
1967 - Bus barns and additional classrooms were added.
1972 - State Wrestling title in Class C
1983 - State Wrestling title in Class D