圆：周长与面积
Circles: Circumference & Area
使用公式 C = πd（或 2πr）和 A = πr² 计算圆的周长和面积，并解决包含圆形部分的组合图形的周长与面积问题。
Calculate the circumference and area of circles using the formulae C = πd (or 2πr) and A = πr², and solve problems involving perimeters and areas of composite shapes that include circular parts
学习证据 / Evidence
- 给定圆的半径或直径，计算圆的周长和面积
- 求由矩形和半圆组成的组合图形的周长或面积
- 非正式地解释 π、直径和周长之间的关系
- Calculate the circumference and area of a circle given its radius or diameter
- Find the perimeter or area of a composite shape made from rectangles and semicircles
- Explain the relationship between π, diameter, and circumference informally
评估问题 / Assessment
如果{{name}}想知道自行车轮子完整转一圈能走多远，能否用轮子的直径和π（圆周率）来算出周长？
If {{name}} wants to know how far a bicycle wheel travels in one full rotation, can they use the diameter of the wheel and π (pi) to work out the circumference?