I second Chris’ suggestion of incorporating chairs, especially if you have a large class and not a lot of wall space. That will also give lower conditioned attendees a place to rest when they need it as well as double as an assistive device they can hold onto when practicing the balance exercises you demonstrate. I recommend starting with simple balance exercises then building progressions on top of that for the more advanced attendees. For example, start with feet together; lower functioning participants can keep a hand on the chair or a wall and practice taking assistance away. From there add progressions for more advanced participants such as closing the eyes, looking around the room, turning the head in different directions or by adding a counter weight as Chris mentioned above. From there just simply change the foot positions (tandem, single leg) and use the same progressions. I would also add some leg strength and reaction time exercises in since they play such a large role in balance.