Setting up a grid and a 1 meter square excavation unit: Staking out the grid: 1.Locate and mark a datum with chalk. 2.Use the compass to find your bearing along a north south and then an east west line. Place a marker at the farthest point you are going to map from the datum along each of those lines (4 or 5 meters). 3.Use the stakes provided to mark 1 meter increments along each line. If you cross concrete, use the chalk to mark increments. 4.Recheck each line orientation with the compass. Then use the total number of meters gridded in each direction, together with the Pythagorean Theorem (see below) to determine the approximate hypotenuse between the two end points. Measure these, and adjust the lines if needed. Use the Pythagorean Theorem: For a square with 1 meter sides, the diagonal should always be 1.41 m (in both directions). For a square with 2 meter sides, the diagonal should always be 2.83 m. Staking out a square: 1. Stake the first corner.