To find the total length of wood needed for the sides of the square sandbox, we need to calculate the perimeter of the square. Since the area of the sandbox is 169 square feet, we can determine that each side of the square is 13 feet long.
To find the perimeter, we multiply the length of one side by 4 (since a square has four equal sides). Therefore, Mrs. Drew would need a total of 52 feet of wood for the sides of the sandbox.