Just a point, without knowing how far up the tree the items were, it's impossible to surmise. If I was that kid that needed those expensive glasses, and I knew I would get a spanking if I lost them, why put them up a tree? Why not lay them gently on my pile of clothes (out of the way) if I was going swimming? Putting them up in a tree would be illogical to me anyway, because gravity. They could break and fall. Surely you would also want them somewhere you could find them if you were indeed poorly sighted. It just doesn't make sense.

Why throw your belt up there as well? You'd have to know that the chances are it will get caught or wrapped around a branch like a bolas. Every kid by that age has thrown at least one thing up in the air that they could never get down. Frisbees, tennis balls, you name it. I'm not saying you're wrong, I just saying that it sounds weird. As I said though, it wasn't specified how high up in the tree, or indeed how high the tree itself was. Those details would change the dynamic significantly or even completely. From - 'throwing (X) items UP into a tree', to 'draping said items gently over a convenient and low hanging branch'. God is in the details.

It's irritating not to have enough information to work with. You're always just postulating. I hope somebody who worked the case, or can work the case now, sees some ideas here and decides - 'What the heck? Let's do some postulating, revisit the investigation, and see what comes up.' One can but hope?