Construction on Koelsch Elementary School began in March of 1956 with students and faculty being housed in Cole and Franklin Schools until the new school was ready for occupancy. It took about nine months for most of the construction.
In December of 1956, students moved into the new building even though there was some construction still to be completed. A dedication of the building was held in February of 1957, honoring Judge Charles Koelsch, for whom the building was named.

Koelsch school was full the first year of operation. In 1957 four classrooms were added. This was enough space for about ten years, then another addition of four more classrooms was made in 1969. A major reroofing and remodeling project was undertaken using levy monies in 1994-95.

Judge Koelsch

Judge Koelsch was born in Wisconsin. He came to Idaho in 1895 and went to work in Senator William Borah's law office as a student clerk. He taught school for a term in South Boise, and was admitted to the bar in 1898. He served as probate judge of Ada county, and as a prosecuting attorney participated in the famous Moyer-Haywood-Pettibone trials.

Judge Koelsch was elected to serve as a representative to the Idaho legislature from Ada county in 1912. After practicing law in private for several years, he was appointed by Governor H. C. Baldridge to serve as district judge.