You'll need a stool and some youth leaders.
Have a youth stand on the stool. Demonstrate that with a little effort, if the person stands alone, you can knock him/her off the perch.
Point out that it's very difficult for someone to Stand in Holy Places all alone. How can they "be not moved?" Scripture study, Prayer, Good Friends, etc, will be common responses. Have the some helpers (youth leaders) come up and stand around the person on the stool representing each topic. After the person is surrounded, ask a priesthood leader to come up and defend the stool. With all these things in place, you can effectively stand in holy places and be protected from the world.
Show that when one of these principles is missing, there could be an opening for Satan to get through.
Open a discussion on how priesthood and other leaders, parents, scriptures all help us maintain our footing and keep us in Holy Places.