测量周长
Measuring Perimeters
测量简单平面图形的周长
Measure the perimeter of simple 2-D shapes
学习证据 / Evidence
- 分别量出长方形的每条边，再把各边长度加起来求出周长
- 已知一条边的长度，计算正多边形的周长
- 解释周长就是图形一周的总长度
- Measure each side of a rectangle and add the lengths to find the perimeter
- Calculate the perimeter of a regular shape given the side length
- Explain that perimeter is the total distance around a shape
评估问题 / Assessment
如果{{name}}想给一个宽20厘米、高30厘米的长方形相框四周装上装饰边，{{name}}能算出需要多长的装饰边吗？
If {{name}} wants to put a decorative border around a rectangular picture frame 20 cm wide and 30 cm tall, can they work out the total length of border needed?