Introducing Angles in a Triangle

Introducing Angles in a Triangle
Introducing Angles in a Triangle
Introducing Angles in a Triangle
Introducing Angles in a Triangle

What's Included

  • Smart Notebooks Presentation
  • Activ Inspire Flipchart
  • Lesson Plan
  • Microsoft PowerPoint Presentation
  • Differentiated Worksheet

Introducing Angles in a Triangle

Building on angles on a straight line and vertically opposite angles students are taught why angles in a triangle have a sum of 180°.  More able students are challenged to prove this using angles in parallel lines.The start of the lesson recaps related angle properties such as those on a straight line and about a point.  The main part introduces the sum of angles in a triangle as 180° and provides several examples for practice.  The plenary challenges students to combine multiple properties within a single problem.
Differentiated Learning Objectives
  • All students should be able to calculate angles in a scalene triangle.
  • Most students should be able to calculate angles in an isosceles triangle and combine other angle properties.
  • Some students should be able to prove angles in a triangle have a sum of 180°.
View online lesson
Lesson Downloads
Download PowerPoint Download Notebook Download Flipchart Download Worksheet
Scheme of Work Link
Angle Properties
Related Blog
Geometrical Reasoning in Key Stage 3
IMMEDIATE DOWNLOAD

Mr Mathematics Blog

Calculating the Volume of a Pyramid

When calculating the volume of a pyramid we can substitute the values of the length, width and perpendicular height into the formula V = 1/3 lwh.  In my experience this is often provided for the students with little explanation as to why a volume of a pyramid is exactly one third the volume of a […]

Solving 3D Problems using Trigonometry

When teaching solving 3D problems using trigonometry we begin the lesson with a recap of Pythagoras’ Theorem and the three trigonometric ratios.  We do this by matching the ratio and equations to the respective right-angled triangle.   Students are encouraged to work in pairs and to show the diagrams as part of the working out on […]

Rounding to a significant figure

When I teach rounding to a significant figure, I ask the class to discuss in pairs or small groups a definition for the word significant.  It is a word that all the students have heard before but not all are able to define. After 2 or 3 minutes of conversation I ask the students to […]