The sum of the angles in the quadrilateral Whiteboard exercise Play

The sum of the exterior angles Animation Play

The sum of the interior angles of a quadrilateral – proof Animation Play

The two sides and an angle between them Whiteboard exercise Play

Theorem – assumptions and claim Student activity Play

Theorem – assumptions and claim Whiteboard exercise Play

Theorems and their assumptions in geometry Student activity Play

Theorems and their assumptions in geometry Whiteboard exercise Play

Trapeziums Animation Play

Trapeziums Student activity Play

Using tangent theorems Whiteboard exercise Play

Using tangent theorems Student activity Play

Variety of organic molecules Animation Play

What is a perimeter? Student activity Play

What is a perimeter? Animation Play