Cut enough pieces of paper or fabric to cover the tiles. You can use enough paper or fabric to completely cover each tile, or cut out a shape or image to attach to the center of each tile.
Work one ceiling tile at a time or one tile per person at a time. Stand on a ladder if you can't take the tiles down. Smooth PVA glue over the tile using a paintbrush or roller, depending on the size of the tile.
Lay the cut-out fabric or paper on top of the tile. Smooth it flat so that there are no wrinkles or bubbles between the paper and tile. Keep working until the tile is sufficiently coated in paper or fabric.
Apply another layer of glue on top of the paper to seal its edges flat and prevent peeling. Let the glue dry overnight.
Repeat the process on the remaining tiles.
Paint a layer of polyurethane over the decoupaged tiles to add a layer of shine. You can skip this step if you wish.