1. **State the problem:** Find the area of the rectangle with vertices at points A(0,1), B(3,1), C(3,-3), and D(0,-3). 2. **Formula for area of a rectangle:** $$\text{Area} = \text{length} \times \text{width}$$ 3. **Find the length:** The length is the horizontal distance between points A and B (or D and C). $$\text{length} = 3 - 0 = 3$$ 4. **Find the width:** The width is the vertical distance between points A and D (or B and C). $$\text{width} = 1 - (-3) = 1 + 3 = 4$$ 5. **Calculate the area:** $$\text{Area} = 3 \times 4 = 12$$ 6. **Answer:** The area of the rectangle is 12 square units.