As in the slide-show demo today, get into a fish head to show first hand that a bony fish has a skull within its skull. I think I convinced my outlaws.
Fish heads are easy to come by.
Sometimes you can get one for free at a local market. You can look up and read about these head skeletal elements in advance of your dissection if you'd like, or not. Much information is available in the library. Write up a short paper describing what you learn. The style and content is left to you, and it should be yours individually, even if you did the exercise with others.