I believe the poured tops are made with epoxy resin. It's a two-part product and must be mixed before using. Google for more information. It's fairly expensive.
One can get very thin sheets of laminate (the Formica material you asked about) at builder's stores that must be glued on. Using this product you might also need to do something to the edges--depends on the table you're covering.
If you can find it, aluminum flashing might come wide enough for the tables and there are sheets of other metal in the big box building stores.
One more option would be to glue linoleum to the tops but I doubt it would be gouge resistant.
If the tables are wooden, sanding and refinishing would be the nicest way.
Good luck and blessings for helping your school.