The Marks Capture Rights module controls which staff members can capture marks for which subjects and grades.
My School > System > Curriculum > Curriculum Setup > Marks Capture Rights
Do Subject Group Teachers get rights automatically? Yes. Staff members configured as Subject Group Teachers (blue) or Subject Heads (pink) are automatically granted marks capture rights for their subjects.
Why can't a teacher see the marks screen? Check that they have both View and Edit rights for module 2.2 Learner Marks assigned here.