角的类型（8岁以上）

运用并理解标准几何图形符号：用小正方形表示直角，用单条或双条短斜线表示相等长度，用弧线表示相等角；用三个字母（如∠ABC）或单个字母、数字表示角；运用这些符号绘制一点周围的角、直线上的角以及多边形内角的图形；并能根据图中的符号识别已知信息，求出未知角。

Use and interpret standard geometric diagram conventions: mark right angles with a small square, equal lengths with single or double tick marks, and equal angles with arc marks; label angles in three-letter notation (∠ABC) and individual angles with a single letter or number; draw diagrams showing angles at a point, angles on a straight line, and angles inside polygons with these conventions; read diagrams with these marks to identify given information and find unknown values

学习证据 / Evidence

• 在图中用小正方形符号标记直角，并解释其含义
• 在图形中用单条短斜线表示相等长度，用双条短斜线表示另一对相等的边
• 读取并解释角符号（如∠ABC），并识别图中所指的角

• Mark a right angle with a small square symbol in a diagram and explain what it means
• Use tick marks to show equal lengths in a shape and double tick marks for a second pair of equal sides
• Read and interpret angle notation (e.g. angle ABC) and identify the angle being referred to in a diagram

评估问题 / Assessment

如果{{name}}的数学图中，一个角处画有小正方形，另外两个角处有相同的弧线标记，{{name}}能否说出每个标记的含义，并利用它们在不重新测量的情况下求出缺失的角度？

If {{name}}'s maths diagram shows a small square in one corner and matching arc marks on two other angles, can they tell you what each mark means — and use them to figure out a missing angle without re-measuring?