Corrections

The student has the possibility to work in a field trip but unfortunately she has another responsibility in a museum exhibition.

She proposes to ask to the other professor if he could hire another student for the job in the museum or the teacher proposes to finish earlier the work in the museum to she could travel the departure day.

I think is better to hire another person for the museum work and she focuses on the field trip exclusively because of the responsibility this carries on, especially for students and tools.