Ah, a practical question! To measure the roofline of your home for Christmas lights, you'll need to use a tape measure. Start at one end of the roof and measure the total length. Then, divide the length by the number of light strands you want to use, and measure that distance on each side of the roof. Finally, measure the height of the roof from the ground to the peak. This will give you the length and height measurements needed to determine how many lights you'll need to cover your roofline.