Properties of Shape - Angles in a Triangle – Missing Angles (3) - Presentation

In the Properties of Shape unit, specifically focusing on Angles in a Triangle, students delve into the task of calculating missing angles. The lesson encourages students to start by recalling and defining the four types of angles, setting a strong foundation for the activities that follow. The first activity challenges students to consider whether estimating angles is a sensible approach before they proceed to calculate the values of unknown angles, denoted by x and y, within a triangle. The activity requires a step-by-step explanation of their working, reinforcing the concept that the sum of angles in a triangle is always 180 degrees, and demonstrating how this knowledge is applied to find missing angles.

Subsequent activities build upon this understanding, asking students to identify the type of triangle they are working with and to consider how this information aids in calculating missing angles. Students work through problems that involve both internal and reflex angles, providing them with a comprehensive grasp of angle calculations in various triangle configurations. Each problem is designed to encourage methodical reasoning and clear presentation of their mathematical working. The lesson concludes with independent work, where students are tasked with calculating the size of identified angles, including reflex angles, and providing reasons for their answers, ensuring they can demonstrate their understanding of angle properties in triangles.