Final answer:
Assigning a single group grade for a project means that all members of the group will receive the same grade, regardless of individual contributions. This can be frustrating if some group members do not put in effort, as it can negatively impact the overall grade.
Step-by-step explanation:
When a teacher assigns a group project and announces that it will be given a single group grade, this means that all members of the group will receive the same grade, regardless of individual contributions.
In this situation, Shilah is likely to groan because she knows that a lack of effort from some group members can negatively impact the overall grade for the project.