Monthly Archives: November 2013


Something I’ve started telling my students regularly, usually when they try to magically change equations to do what they want.

Why is there no math (or maths) class at Hogwarts? They have Charms, Potions, Defense Against the Dark Arts…but no math. Why?

Because there is no magic in math.

The point is that there is a reason for everything we do in math. 5+3=3+5? Commutative property. “Moving” something to the other side of an equation by subtracting it from both sides? Equality property. Getting rid of a fraction by multiplying by the reciprocal? Multiplicative inverse property.

There is no magic in math.