Geometry Basics · grades 6–8

Geometry Basics.

Shapes and space — angles, triangles & polygons, perimeter & area, and the surface area & volume of solids. Every lesson draws the figure so you see exactly what you're measuring.

Angles

Measure & relate.

1.1
Types of angles
Acute, right, obtuse, straight.
1.2
Complementary angles
They add to 90°.
1.3
Supplementary angles
They add to 180°.
1.4
Vertical angles
Across a crossing — equal.

Triangles & polygons

Angle sums & types.

2.1
Triangle angle sum
Always 180°.
2.2
Types of triangles
By angles & by sides.
2.3
Polygon angle sum
(n − 2) × 180°.
2.4
Quadrilaterals
Name by properties.

Perimeter & area

Around and inside.

3.1
Perimeter
The distance around.
3.2
Area of rectangles
Length × width.
3.3
Area of a triangle
½ base × height.
3.4
Parallelograms & trapezoids
Base, height, average.
3.5
Circles
Circumference & area.

Surface area & volume

Solids in 3D.

4.1
Volume of a box
Length × width × height.
4.2
Surface area of a box
All six faces.
4.3
Volume of a cylinder
Base circle × height.
4.4
Triangular prisms
Triangle base × length.

Apply

Real measurements.

5.1
Flooring & paint
Area in the real world.
5.2
Tanks & containers
Volume in the real world.
5.3
Wheels & gardens
Circles in the real world.

Capstone

All shapes.

C1
Every shape
Angles, area, volume — mixed.

Geometry Basics.

Angles

Types of angles

Complementary angles

Supplementary angles

Vertical angles

Triangles & polygons

Triangle angle sum

Types of triangles

Polygon angle sum

Quadrilaterals

Perimeter & area

Perimeter

Area of rectangles

Area of a triangle

Parallelograms & trapezoids

Circles

Surface area & volume

Volume of a box

Surface area of a box

Volume of a cylinder

Triangular prisms

Apply

Flooring & paint

Tanks & containers

Wheels & gardens

Capstone

Every shape