Properties of Shape - Angles in Regular Polygons - Presentation

In this educational presentation, students are introduced to the topic of angles within regular polygons. The lesson begins with a discussion about the definition of a polygon and what constitutes a regular polygon, encouraging students to draw and name an example on their whiteboards. The main focus of the lesson is to equip students with the skills to calculate the sum of interior angles in various regular polygons. The first activity asks students to consider the sum of interior angles in a triangle, then to draw a quadrilateral, partition it into two triangles, and calculate the sum of angles within each triangle. This leads to the discovery that the sum of angles in a quadrilateral is 360°, reinforcing the concept that a quadrilateral can be considered as composed of two triangles.

Building on this understanding, the second activity involves completing a table by using the same method of partitioning polygons into triangles to find the sum of their internal angles. Students fill in the table for polygons such as pentagons, hexagons, and heptagons, noticing a pattern and making predictions for other polygons. The presentation further challenges students with reasoning tasks, where they must use clues to deduce the type of polygon being described based on the sum of its interior angles. Independent work tasks encourage students to apply what they've learned by drawing polygons, partitioning them, and solving for unknown angles. Finally, the discussion section prompts students to reflect on patterns observed in the table and to make predictions, solidifying their understanding of the relationship between the number of sides in a polygon and the sum of its interior angles.