Properties of Shape - Angles in a Triangle (1) - Planning

In a Year 6 mathematics lesson focused on the properties of shapes, students delve into the world of triangles, specifically exploring the sum of interior angles. The lesson begins with a practical task where students use coloured card to create various types of triangles, including equilateral, isosceles, scalene, and right-angled. By measuring and summing the interior angles with a protractor, they discover a consistent total of 180 degrees, regardless of the triangle type. Through partner discussions, they compare the triangles and reaffirm that while side lengths may differ, the angle sum remains constant. A clever demonstration of this involves tearing off the corners of a triangle and aligning them to form a straight line, visually proving the 180-degree sum.

Further activities have students calculate missing angles by using the knowledge that the sum of a triangle's angles is always 180 degrees. They learn to identify the type of triangle based on the angles, with scalene triangles having all different angles, isosceles having two equal angles, and right-angled triangles featuring a 90-degree angle. Group work and differentiated worksheets help to consolidate this understanding through reasoning and fluency exercises. The lesson aims to correct common misconceptions and reinforces that the size of the triangle does not affect the sum of its interior angles. In conclusion, students reflect on the skills they've used, such as identifying right angles and performing addition and subtraction, and commit to remembering the key learning points from the lesson.