# Tagged: Thales’ Theorem

# Diagram Deficit II: Andy’s Fallacies

**Overview**

This is written in response to @OldAndrewUK’s polemical apology for bad mathematics at Michaela Community School entitled “*The Truth About Calculating Angle Questions*“, which itself was written in response to me. You will not find the document on his blog, which he has cultivated for over a decade and to which most people would refer for his views, perhaps ashamed of its content. With good reason.

# Fixing The Diagram Deficit

My last post, Michaela’s Knowledge Deficit, is proving very popular and has led to a lot of twitter discussion around the issues of qualifications appropriate to subject specialists and desirable standards for mathematical resources. Upon looking at the incorrect diagrams discussed in that post many people, like me, had a WTF moment while others could not quite place their brains on what it was that troubled them about what they saw. I hope in exposing the incorrect nature of one of these mind-bending, eye-twisting blots that I can help readers to understand the long-term implications of not challenging such incorrect material and thus motivate them to greater concern for the standard of maths currently being delivered by some schools and personnel, perhaps even to your own children.