Enrollment continued to grow, and a second building was added to the Junior Elementary School campus in the late 1920s, but still larger facilities were deemed necessary to accommodate future growth and additional grade levels.
Coonley chose a wooded tract in Downers Grove, adjacent to the Maple Grove Forest Preserve, as the site for the new building, and her son-in-law, Waldron Faulkner, became the architect of the new building project.
Over one hundred students attended school in the opened building on September 30, 1929, and it was renamed The Avery Coonley School, in honor of Coonley's late husband, who had died in 1920.
Coonley chose an unusual mascot to represent the ideals of the school.
She felt a seahorse was an example of a unique creature who was also a member of a larger community—an analogy for her vision for Avery Coonley.
The seahorse swims upright, from which derives the school motto: "Onward and Upward", and representations of seahorses are reflected in decorative ironwork and the weather vane on the 1929 building.

Progressive education, a pedagogy promoting learning through real-life experiences, was at its zenith in the United States in the 1920s and 30s, and the Avery Coonley School was a widely known model of these theories in action.
Avery Coonley was featured regularly in Progressive Education and other professional journals, and in 1938, the editor of Progressive Education, Gertrude Hartman, published a profile of the Avery Coonley School in her book Finding Wisdom: Chronicles of a School of Today.
She noted, "[v]isitors from all parts of the United States and from foreign countries [came] to see the school—sometimes as many as thirty in a day."
Hartman described in great detail the curriculum and daily life of the school, which had by then added a seventh and eighth grade, commenting that 
the most noticeable thing about it is the spirit of earnestness and joy which pervades it ... There is a fundamental philosophy of life and education underlying the work of the school, which gives clear direction to all its activities.
Broad areas are planned, which form the framework of the curriculum.
These however are flexible and subject to modification depending upon conditions.

 The book described the progress of the students from their first year of kindergarten through their ten years of study, capturing in photos, stories, and examples of students' work their encounters with nature, history, art and other subjects through creative play and collaborative projects.
She concluded with observations about the importance of the daily life of the school in developing social responsibility: 
It is the belief of those concerned with the school that out of the kind of education described here will emerge more socially enlightened members of society than the education of our generation has produced ... The method in which those in the school place their faith is the building into the very nature of growing boys and girls, through their growing years, those qualities of mind and spirit from which alone a new attitude towards human relations can evolve.

 
Finding Wisdom became a classic in the education field and solidified the Avery Coonley School's national reputation as a model of progressive education.

Morse died in 1940, after 34 years as director, and several years went by without a strong local leadership.
To ensure a sounder footing for the future, Coonley merged Avery Coonley with the National College of Education (NCE, formerly the Chicago Kindergarten College and now National-Louis University) in Evanston, Illinois, in 1943.
The two institutions had close ties dating back to Morse's Kindergarten College days, and the arrangement took advantage of the NCE's financial and teaching resources while Avery Coonley provided a living laboratory for teacher training and educational research.
Under NCE management, ACS continued to offer a curriculum that emphasized practical learning, outdoor education—including farming—and hands-on activities like automobile repair.
German and French were added in 1949, with stud
Enrollment continued to grow, and a second building was added to the Junior Elementary School campus in the late 1920s, but still larger facilities were deemed necessary to accommodate future growth and additional grade levels. Coonley chose a wooded tract in Downers Grove, adjacent to the Maple Grove Forest Preserve, as the site for the new building, and her son-in-law, Waldron Faulkner, became the architect of the new building project. Over one hundred students attended school in the opened building on September 30, 1929, and it was renamed The Avery Coonley School, in honor of Coonley's late husband, who had died in 1920. Coonley chose an unusual mascot to represent the ideals of the school. She felt a seahorse was an example of a unique creature who was also a member of a larger community—an analogy for her vision for Avery Coonley. The seahorse swims upright, from which derives the school motto: "Onward and Upward", and representations of seahorses are reflected in decorative ironwork and the weather vane on the 1929 building.
Progressive education, a pedagogy promoting learning through real-life experiences, was at its zenith in the United States in the 1920s and 30s, and the Avery Coonley School was a widely known model of these theories in action. Avery Coonley was featured regularly in Progressive Education and other professional journals, and in 1938, the editor of Progressive Education, Gertrude Hartman, published a profile of the Avery Coonley School in her book Finding Wisdom: Chronicles of a School of Today. She noted, "[v]isitors from all parts of the United States and from foreign countries [came] to see the school—sometimes as many as thirty in a day." Hartman described in great detail the curriculum and daily life of the school, which had by then added a seventh and eighth grade, commenting that 
the most noticeable thing about it is the spirit of earnestness and joy which pervades it ... There is a fundamental philosophy of life and education underlying the work of the school, which gives clear direction to all its activities. Broad areas are planned, which form the framework of the curriculum. These however are flexible and subject to modification depending upon conditions.
 The book described the progress of the students from their first year of kindergarten through their ten years of study, capturing in photos, stories, and examples of students' work their encounters with nature, history, art and other subjects through creative play and collaborative projects. She concluded with observations about the importance of the daily life of the school in developing social responsibility: 
It is the belief of those concerned with the school that out of the kind of education described here will emerge more socially enlightened members of society than the education of our generation has produced ... The method in which those in the school place their faith is the building into the very nature of growing boys and girls, through their growing years, those qualities of mind and spirit from which alone a new attitude towards human relations can evolve.
 
Finding Wisdom became a classic in the education field and solidified the Avery Coonley School's national reputation as a model of progressive education.
Morse died in 1940, after 34 years as director, and several years went by without a strong local leadership. To ensure a sounder footing for the future, Coonley merged Avery Coonley with the National College of Education (NCE, formerly the Chicago Kindergarten College and now National-Louis University) in Evanston, Illinois, in 1943. The two institutions had close ties dating back to Morse's Kindergarten College days, and the arrangement took advantage of the NCE's financial and teaching resources while Avery Coonley provided a living laboratory for teacher training and educational research. Under NCE management, ACS continued to offer a curriculum that emphasized practical learning, outdoor education—including farming—and hands-on activities like automobile repair. German and French were added in 1949, with stud
Avery Coonley School