Remove all of the 2-by-4 ceiling tiles from the drop ceiling grid, and count how many tiles you have. Purchase one additional grid divider per ceiling tile.
Cut the tiles to size. Measure and mark the center of the tile on the 4-foot length. You will convert a 2-by-4 ceiling tile to two 2-by-2 tiles by cutting the rectangular tile into two square sections. Draw a line from the center mark to divide the tile in half. Cut along this line with a utility knife.
Reinstall the tile. Insert a grid divider directly in the center of the old 2-by-4 grid to create two smaller 2-by-2 grids. Insert the two 2-by-2 ceiling tiles, placing one on each side.
Complete the ceiling. Repeat Steps 2 and 3 until the entire ceiling is fully installed.