📚 Topic Summary
A sphere is a perfectly round 3D object where every point on its surface is the same distance from its center. The radius is the distance from the center of the sphere to any point on its surface. The diameter is a straight line passing through the center of the sphere, connecting two points on the surface. Importantly, the diameter is always twice the length of the radius.
Understanding the relationship between the radius and diameter is crucial for calculating other properties of spheres like surface area and volume. Knowing these basics unlocks a deeper understanding of geometry and its applications in the real world.
🍎 Part A: Vocabulary
Match the term to its correct definition:
| Term |
Definition |
| 1. Radius |
A. A straight line passing through the center of the sphere connecting two points on the surface. |
| 2. Diameter |
B. A perfectly round 3D object where every point on its surface is equidistant from the center. |
| 3. Sphere |
C. The distance from the center of the sphere to any point on its surface. |
| 4. Circumference |
D. The distance around the sphere. |
| 5. Center |
E. The point equidistant from all points on the surface of the sphere. |
✍️ Part B: Fill in the Blanks
Complete the following paragraph using the words: radius, diameter, twice, center, sphere.
A ______ is a 3D shape where all points on the surface are equally distant from the ______. The ______ is the distance from the center to the edge, while the ______ goes all the way across the sphere through the center. The diameter is always ______ the length of the radius.
🤔 Part C: Critical Thinking
Imagine you have a spherical ball of clay. You know the diameter is 10 cm. If you cut the ball perfectly in half, what would be the radius of the circular face you created? Explain your reasoning.