Identifying Expressions, Equations, Identities and Formulae

A lesson (ppt) to go through the differences between expressions, equations, identities and formulae.
Starter involves getting students to write their own definitions of an expression before discussing as a class which is the best definition.
Main tasks include being given definitions for the equations, identities, and formulae. Simple equations to solve, '2 facts 1 lie' type activity for identifying identities, formulae to substitute into and work out the value of a variable.
After these an activity that involves students stating whether something is an expression, equation, identity or formula, answers included. Then, a '2 facts 1 lie' and review of learning plenary at the end of the lesson.