### Instruction: In China, spheres are used to exercise a person's hands. If the diameter of a sphere is 2 inches, how many square inches are in its surface area? Express your answer in terms of $\pi$.### Response: I know that the surface area of a sphere is given by the formula $4\pi r^2$, where $r$ is the radius of the sphere.
Since the diameter of the sphere is 2 inches, the radius must be half of that, or 1 inch.
Plugging in 1 for $r$ in the formula, I get $4\pi (1)^2 = 4\pi$ square inches.
That's the answer, but I can also simplify it by writing $4\pi$ as $2\cdot 2\pi$ or $2(2\pi)$.