Instructional Assistant to make lesson plans?

Can someone explain this task? The job requires that the IA make lesson plans based off of curriculum. Also they must be able to do the lessons when the teacher is out sick or on PTO. The IA is there for the normal tasks of being with the children in class, lunch, recess, and bathroom. And is there to teach things one on one/ in a group when the kids need help. Additionally, the teacher can assign the IA to be in charge of meetings (not sure what this means). The job doesn't require a teaching degree so I'm wondering why the lesson planning tasks?