When your students don't know much about showing livestock, then you get creative when demonstrating it. Commerce FFA broke out the show sticks and beach balls so that their Greenhand Middle Schoolers could get a crash course in showmanship.
When you think about it, the activity makes perfect sense. You are covering some very basic principles in a controlled environment. It's a controlled environment because there's no live animal that can run away, the room is a familiar place for the student, and as an advisor you have more control of the situation and can reset everyone without herding livestock back into position. So lots of pluses there.
In terms of basic principles, your students can work on eye contact, keeping the correct distance between themselves and the hog, keeping an appropriate distances between themselves and the judge, and remaining conscious of where the hog is moving and how to correct that movement with the show stick. Fortunately, beach balls don't have a mind of their own which makes the first practices much easier on your students.
While we don't carry many teaching materials on livestock judging, we do have livestock anatomy posters and livestock anatomy worksheets which will come in handy as you teach your students the parts of each livestock species and how they are important in livestock judging and showing.