I have a 10 month old female, and I've seen plenty of videos of dragons fighting their reflection, playing with tennis balls, cat toys, and stuffed animals, etc. I've tried all of these things, but she just doesn't seem to get it. Is there are reason she doesn't understand any of these things? Are female bearded dragons less likely to play?
All dragons are different really! Some like to just relax, and others act like they need medication to calm down LOL!
Part of the joys of dragon owning, they are all different.
That being said, maybe you just need to find her thing.
Is she very active right now or does she kind of just lay around her tank all day?
Is your husbandry OK and her diet ok? She will obviously need those things in order to have the energy to be a wild child.
My male (7 mo.) doesn't "get" toys either, but boy, does he love to climb and play, "the floor is lava"--figuring out ways of doing laps around the enclosure while never touching the substrate. (He did/does this all by himself--not sure there's any way teach it.) Moving stuff around provides him with more opportunities/ways to explore.