There is an arrow drawn on the head of the boy roughly in the middle of the picture below.
He would be related somehow to the Ohrt/Mohr family.

I knew I recognized the teacher but couldn't think of her name, so I searched my database to find files with the name "grade" in them.
I found other 8th grade pictures in sure enough there was the same teacher and one of the files had Verna Schmidt.
So I searched for Verna Schmidt in my teacher records.
She taught from 1912 through 1918.
Then I searched for Mohr boy names for this time-frame and found Henry which is a different Mohr family.
Then I searched for Ohrt and found that Julius Ohrt did not graduate but was with the class of 1919.
When we published the Manning Schools book I had about 10 volunteers go through the school records to find all of the names recorded each year in school and the years they attended.
I don't have all of those individual years recorded in my database but I do have the hard copy records, so I dug them out.
I looked up 1919 and amazingly Julius Ohrt was listed as attending ONLY 1915, and that was the 8th grade.

So I am fairly sure the boy with the check mark is Julius Ohrt and below are the names of the students who were members of the class of 1919 - some who graduated and others who, for various reasons did not finish at Manning.
Some of the names in the list are rural students so they would have been in country school in 8th grade and NOT in this town school picture.

8th grade class - Verna Schmidt, teacher

1919 MHS graduates: Clifford Best, John R. Hansen, Francis Hickey, Viola Horn, Graydon Illsley, Lillian Johnson, Elma Mayer, Raymond Motter, Trella Ramsey, Helen Rohr, Victor Schultz, Eula Sweger

1919 Former students: Edith Bailey, Clarence David, Lillian Dethlefs, Marina Eike, Hazel Foster, Harry Frahm, Fred Fritz, Julius Grau, Myron Gray, Elsie Hansen, Fred Hessling, Elva Lohrmann, Alfred Meyers, Lila Monk, Julius Ohrt, Louis Ossenkop, Florence Sammin, Minnie Schmidt, Genevieve West