For stratification you need to revise the theories for each type of identity and make sure that you have evidence for a 10 mark question on how either a group is advantaged or disadvantaged for each type of identity. Use material you are already revising e.g. certain ethnic groups may be disadvantaged by underachieving in the education system or being more likely to be imprisoned in the criminal justice system. Stratification should pull from all of your other topics in terms of why certain groups do better than others in society.