Key stage 3 mathematics for using Pythagoras' Theorem to calculate any length of a right-angled triangle. Learning progresses from working with Pythagorean Triples to calculating the area of a right-angled isosceles triangle when only the hypotenuse is given.

At the start of the lesson students attempt to find the difference of two hypotenuse lengths in a composite shape. The plenary challenges students to apply Pythagoras' Theorem to a complex shape made from two triangles.

**Differentiated Learning Objectives**

- All students should be able to calculate a smaller side of a Pythagorean Triple
- Most students should be able to calculate any side of a right-angled triangle using Pythagoras’ Theorem
- Some students should be able to apply Pythagoras’ Theorem to composite triangular shapes.