Final answer:
The area of the poster board is 1 square yard, calculated by multiplying the length (1 yard) by the width (1 yard).
Step-by-step explanation:
To find the area of a rectangle, you multiply the length by the width. If the length of the poster board is 1 yard and the width is 1 yard, then the area is simply 1 yard × 1 yard, which equals 1 square yard. No further multiplication is necessary since both dimensions are in yards, and we're looking for the area in square yards.