The child uses the ruler and the black marker to draw the outer walls of the house as a large rectangle or L-shape across the sheet. Then divide the inside into rooms by ruling internal walls, leaving gaps for doorways. Five to eight rooms gives plenty of detail without crowding the sheet.
In each room, draw what lives there in small, detailed illustration: a coffin in the basement, a cauldron in the kitchen, a ghost hovering in the attic. There is no need to fill every centimetre; some rooms can be mostly empty to suggest an abandoned feel.
Label every room in clear hand-lettering using a coloured marker. Add a compass rose, a title banner across the top reading "Haunted House" and, if time allows, a small legend in one corner explaining any symbols used. Roll the finished map and store in a cardboard tube to keep it flat.