Mathematics
Geometry
Conceptual
8–9 yrs
Understanding angles (age 8+)
理解角（8岁以上）
Description
Understand that shapes in different categories may share attributes defining a larger category; classify quadrilaterals (rhombuses, rectangles, squares) and draw examples of quadrilaterals not in those subcategories
Mastery Evidence
- Explain that a square is a special rectangle and also a special rhombus
- Sort shapes into a Venn diagram: quadrilaterals vs rectangles vs squares
- Draw a quadrilateral that is not a rectangle, rhombus, or square
Assessment Prompt
If you show your child a square, a rectangle, and a rhombus, can they explain what makes them all quadrilaterals — and what makes each one different from the others?
