An alarming sign at VBS?

Last night, in Vacation Bible School, the theme was "Jesus gives us the power to be brave." The Bible story linked to that was Peter walking on the water.

In order to make it a bit interactive, we had a plastic container filled with several inches of Ooblech (or Slarch, or Gak, or whatever name you prefer) tinted slightly blue. For the uninitiated, Ooblech is a dense mixture of cornstarch and water that make up a "Non-Newtonian Fluid." It acts like a thick liquid (gravy or wallpaper paste) until pressure is exerted on it. Then it acts like a solid.

If you step quickly across the surface of the stuff, your feet won't get wet or very sticky. If you're too slow, you'll begin sinking. We had the kids take off their shoes and socks and try it out. It worked very well. Then, we decided to try letting them sink in it.

That's all fine and good, but remember what I said about how exerting pressure on the Ooblech makes it act like a solid? When you try to lift your feet out, the slime above your feet locks up, and you're good and stuck! The look of horror that came creeping across their young faces as they realized their dilemma was very rewarding! I'd take their hands and tell them to slowly remove their feet, and then they succeeded. Oddly enough, the kids enjoyed the sinking and being stuck fast more than they enjoyed walking across the top.

The upshot of me telling this story is that Peter's ability to walk across the surface was an expression of his faith in Christ, and his sinking signified a wavering in that faith. If the young people preferred the sinking to the walking, what does that say about their spiritual walk?