TES Maths Resource of the Week
What is it?
Often the simplest of ideas make the best resources and that is certainly true of this activity. Ideal as a starter, students begin by practising their substitution skills, before being challenged to work out which of four expressions give the biggest answer.
This seemingly basic task reveals a richer side as the expression that gives the biggest value depends on the substituted values of x. Hence, we move very quickly from simple substitution to trial and error, equation solving, graph sketching and much more.
How can it be used?
This lesson could be used with any year group that is comfortable with the process of algebraic substitution, as the skill of trying out different values of x in a systematic way forms the basis of this task.
Depending on the class, it may be down to you to suggest the idea of plotting the expressions on a graph to see how this could help. The author suggests using Autograph for this but, as I demonstrate in the video above, Desmos is an equally suitable, free alternative.
If you needed any more reasons to try this out, you might like to know that one of the expressions is an exponential one. This, of course, makes it perfectly suited to the new GCSE maths specification.
Craig is a secondary maths teacher in the North of England.
Did you know you can keep up with the latest blog posts in our dedicated maths area?