The picture is captioned:
2. A SQUAD OF TWO HUNDRED GIRLS AT FREE BODY MOVEMENT.
Some of the girls are wearing pinafores, and others are wearing sailor suits.
The lesson must have been rather vigorous, because some of them appear to have dropped their hats/scarves.
This photograph is part of a series of activity sheets, demonstrating lessons in various British schools, in Edwardian times.
I am not sure of the history of the pictures.
They look as if they were originally in some sort of album or folder.
Perhaps they were from a teachers' manual or similar?
The photograph measures around 8" x 4.75" (20 cm x 12 cm).
It is printed on a plain sheet of paper, around (the sort that was commonly used for "book plates" in Edwardian times).
This sheet is about 12.5" x 7.75" (32 cm x 20 cm) . It has been cut (rather unevenly) along one side, presumably when it was removed from its original album or folder.