The numbers in the rectangles Animation Play

The numbers on the diagram Whiteboard exercise Play

The perimeter of the rectangle Whiteboard exercise Play

The Professor's number Animation Play

The recipe Animation Play

The unknown on both sides of the equation Student activity Play

The unknown on both sides of the equation Whiteboard exercise Play

The unknown on one side of the equation Student activity Play

The unknown on one side of the equation Whiteboard exercise Play

The unknown on one side of the equation – more difficult problems Student activity Play

The unknowns Whiteboard exercise Play

The value of the number m Whiteboard exercise Play

The weight of one lemon Animation Play

Think of a number Student activity Play

Think of a number Whiteboard exercise Play

Unknown angle in a triangle Animation Play

Unknown side of a triangle Animation Play

Using linear equations to solve practical problems Student activity Play