Quoting from the article: "Apps for Education is used by K-12 schools and institutions of higher education throughout the world..."
Go to the Apps for Education page at Google, select "Customers", choose "K12" and it lists 10 primary and secondary education school systems as profiled "customer stories".
For example, "Saline Area Schools is a suburban/rural public school district of 5,450 students K-12 located in southeast Michigan, about 50 miles west of Detroit." ... "Encouraged by the success with faculty and staff, the Saline IT team will soon roll Google Apps out to their 3,200 students in grades 5-12."
That is "not the full list". That is a list of "customer stories", and certainly a subset of the full list.
In fact, it's the site I suggested you visit. Next, use the pull-down under "all types" to see that the three targets are "K12", "Organization", and "University".
Go to the Apps for Education page at Google, select "Customers", choose "K12" and it lists 10 primary and secondary education school systems as profiled "customer stories".
For example, "Saline Area Schools is a suburban/rural public school district of 5,450 students K-12 located in southeast Michigan, about 50 miles west of Detroit." ... "Encouraged by the success with faculty and staff, the Saline IT team will soon roll Google Apps out to their 3,200 students in grades 5-12."
https://docs.google.com/file/d/0B5AOHQcS-cAeODQ3MGVkNGEtNzJm...