Welcome back to Chalk Dust and Common Sense, I am Ciara Mulvaney. This week we go to the place where most people's relationship with maths quietly ended: algebra. One day it was numbers, the next day there were letters, and nobody told you why. I have a guest who can explain it better than any textbook. Donal Fitzgibbon has been a carpenter in Limerick for 30 years. He builds staircases, and every staircase involves an unknown he has to work out from what he already knows. He does it on a scrap of plywood with a pencil. He has never once called it algebra. Listen to him work through a real job and I think the letters will finally make sense. Pause and try the staircase yourself when I tell you to. You are listening on Witspeak Podcasts.