This 1923 photo is of the girls section. When it opened it would have been a substantial school with junior and senior pupils. It seems to have lost its senior students in the re-organisation of the 1920s/30s. Here's an extract from the British History online site. Viv.
MARY STREET COUNTY PRIMARY SCHOOL, Balsall Heath.(27) Mary St. Bd. Sch. opened 1 Apr. 1878 (25) by King's Norton Sch. Bd. Accom. 820 Boys, Girls, Infants (21) Fees all 1d.(22) It was the first permanent sch. in new buildings opened by the Bd.(25) Enlarged 1883. Altered and reorganized 1928–33 for Junior Mixed, Infants. Damaged by enemy action 1940. Depts. united 1944. Repaired and altered 1950.(21) Accom. 1955: 17 classrooms, hall.(28)