Here be dragons

These are the dragon tiles in a Mah-jong set. There are four green dragons, four red dragons and four white dragons. No-one knows why the white dragon is a square. Some sets have letters in the corners of the dragons but they aren't very helpful.
The beginners Mah-jong class was transferred to my house this afternoon at the last minute because of sickness. We had two tables of four and I played on one table while listening out on the other to offer help if necessary. And my goodness, it was necessary! They have been playing for eighteen months and some of them are still very confused. I can't believe some of the things they come out with! I would much rather play with my grandson George who learnt when he was about six and picked it up so easily.
At the end of the afternoon I was shattered. Another cup of tea was called for!