Polygon-Not a polygon worksheet - Free Printable

Let me work through this polygon sorting problem step by step.

First, I need to understand what makes something a polygon:
- A polygon is a closed shape made of straight line segments
- It must be closed (no gaps)
- All sides must be straight lines (not curved)
- The lines connect end-to-end

Now let me examine each shape:

Top row:
1. Blue pentagon - Has 5 straight sides, closed shape ✓ POLYGON
2. Red semicircle - Has a curved edge ✗ NOT A POLYGON
3. Orange diamond/rhombus - Has 4 straight sides, closed shape ✓ POLYGON
4. Yellow arrow - Has straight sides and is closed ✓ POLYGON
5. Green shape with curved top - Has a curved edge ✗ NOT A POLYGON

Bottom row:
6. Pink wavy line - Not closed, has curves ✗ NOT A POLYGON
7. Purple heart - Has curved edges ✗ NOT A POLYGON
8. Green triangle - Has 3 straight sides, closed shape ✓ POLYGON
9. Yellow open angle - Not closed (has a gap) NOT A POLYGON
10. Gray square/rectangle - Has 4 straight sides, closed shape ✓ POLYGON

Let me verify my count:
- Polygons: pentagon, diamond, arrow, triangle, square = 5 shapes
- Not polygons: semicircle, green curved shape, wavy line, heart, open angle = 5 shapes

This matches the number of boxes provided (5 for each category).

Final Answer:

Polygons:
- Blue pentagon
- Orange diamond
- Yellow arrow
- Green triangle
- Gray square

Not a Polygon:
- Red semicircle
- Green shape with curved top
- Pink wavy line
- Purple heart
- Yellow open angle