Culmsee Chelmza Gymnasium

Königliches Realprogymnasium Culmsee (postcard sent 1939) with its seal badge in comparison photo from 1943

...the postcard must be older reasonned by the trees at the photograph...

Gymnasium = grammar school / secondary school

Siegelmarke (seal badge)

Königliches Realprogymnasium Culmsee

Gymnasium = grammar school/ secondary school

and

„Realprogymnasium“ former days at Prussia in 1880ies had been secondary school without „Prima“ = without final class before secondary-school examination