This course lays the foundations of geometry. It starts with points, line segments, lines and rays, and how lines can meet. It then measures angles in degrees, names the kinds of angle, and uses pairs of angles such as complementary, supplementary and vertically opposite angles to find unknown angles. Parallel lines cut by a transversal lead to the angle sum and exterior angle properties of triangles. The course goes on to quadrilaterals and polygons, their angle sums and special properties, and ends with the parts of a circle. Each lesson has worked examples and practice with answers.
Primary Years
Plane Geometry (Level 1)
The building blocks of geometry: points, lines and rays, angles and pairs of angles, parallel lines, triangles, quadrilaterals and polygons, and the parts of a circle.
- 7 lessons
Overview
Lessons
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Points, lines and rays
Points, line segments, lines and rays, how to name and write them, collinear points, and lines that meet, never meet or all pass through one point.
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Angles and their types
What an angle is, measuring in degrees with a protractor, acute, right, obtuse, straight and reflex angles, and angles on a clock face.
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Pairs of angles
Complementary and supplementary angles, adjacent angles, linear pairs, vertically opposite angles and angles at a point, used to find unknown angles.
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Parallel lines and a transversal
Corresponding, alternate and co-interior angles, what they tell us when the lines are parallel, and how to test whether two lines are parallel.
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Triangles
Parts and kinds of triangles, the angle sum of 180°, isosceles and equilateral triangles, the exterior angle property, and which lengths make a triangle.
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Quadrilaterals and polygons
Names of polygons, diagonals, angle sums of quadrilaterals and polygons, exterior angles, and the properties of parallelograms and other special quadrilaterals.
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Circles
Centre, radius, diameter, chord, arc, sector and segment, and how to tell whether a point is inside, on or outside a circle.