In Europe they have agreed on a framework for the levels of language skills.
It states what a learner should be able to achieve at a certain level, from A1, basic to C2 proficient.
Maybe this can help you as a guideline how to express the skills of your students to answer the question "What are they able to do?"
Here is the link with the template
http://www.coe.int/T/DG4/Portfolio/?M=/ ... evels.html