Plaques: Class of 1936

I have a folder full of pictures of the various plaques around town, and I think I have found most of them, but every once in a while I stumble upon another one. At the end of April I found one that I had either never noticed or that I had totally forgotten in Hal Gray Park. It seems to be the dedication plaque for this rather new Norway maple.
It simple states, "Dedicated by the Class of 1936 Rensselaer High School." Anyone know more about it?
Other plaques in Hall Gray Park are this one and that one.

Here is the tree more recently. It was one of the last trees to shed it leaves.

Does anyone know the story behind this plaque? Why did this class decide to plant a tree in this park?