Tips for Teachers 128: Get oiled up.
In your classroom, you probably have a whiteboard, some marker pens, and an eraser (aka board rubber).
Unless you're in Germany or the 1970s, in which case you have a blackboard, some sticks of chalk (which is actully gypsum), and a board rubber (aka eraser).
Even in Bulgaria I had a whiteboard, but German schools are literal chalk-and-talk. Retro if you like it, Altmodisch if you don't.
Now, I have a new whiteboard. It's big (2 meters by 1.5), very nice looking, and - because this is Saudi Arabia - Made-in-China and Damaged-in-Transit.
There's also a label saying "Please remove protective film before use"...and no sign of protective film.
And last night it took me an hour to clean off the board marker from the lesson. It seems marker ink doesn't clean off easily, even with water, on new boards.
The reason it doesn't is that the ink is soluable in oil but not water. That's why grimy fingers can sometimes remove what clean cloth can't. The ink itself contains oil, but you need to write a few lessons on the board for enough oil to build up to clean it easily.
Either that...or smear some mayonnaise from your packed lunch on the board, and rub it around. Which is what I did. And it worked.
Nice, clean board, smelling slightly of delicatessan, ready for the next class.
But in case you think my class isn't classy, I also got some extra-virgin olive oil. For the sophisticated TEFLer to rub around.