Anne Frank, in her diary, writes that Betty Bloemendal was a diligent student...but 'more recently' she was not so diligent - of course, it was during the War, and the Holocaust. They were together as classmates and friends for the years 1941-42.
Anne rather snobbishly commented that Betty came from a 'poor' family. Of course, Anne was a young girl, and did not know any better regarding this rather unkind comment. By comparison to Anne's family, who were fairly wealthy (her father owned a factory, and they had a large house), yes the Bloemendals were more modest.
Abraham worked as an insurance clerk. His father was a butcher and owned a butcher shop (Kosher) in the centre of the Jewish district in Schoolholm, Groningen. Jochwet (Jeanette)'s father was a teacher of Torah and Yiddish.