They carried out research into teachers' stereotypes - they showed 96 teachers pictures of children from all backgrounds and asked them to rate who would be the most successful.
Harvey and Slatin
The children who were white and looked like they came from middle class backgrounds were rated as more successful than the children from ethnic minority groups or those who looked like they came from poor backgrounds.
Harvey and Slatin
This research is a little dated now and only applies to the US so is culturally restricted