Something I got for tuition

So yea...
I went for my add maths tuition a little early this week.
My teacher replaced this week's Friday class yesterday.
So as usual, her kids were there...
Nothing much usually comes from the kids....
And her eldest son....
He proved something....
O yes he did...
He proved that he was just too smart for all of us there in the tuition centre

Since it was a public holiday, the whole family was at home...
Mr. Vincent, my tuition teacher's husband decided to do some carpenting outside, with his sons
So her eldest son, let's call him Timothy; came in with a piece of wood( whoa there!)
Let me tell you the conversation
T: Timothy
A: Amma( that's what the children in the family call my teacher)

T:Amma! I want a pen!
A:* Searches the stationary holder* Here you go
T: Thanks Amma...*runs out, then comes in again* Amma! This pen got no ink!
A: Oh sorry....Here *Gives another pen*
T:*runs out again, then runs in* AMMA! NO INK! Give me that pen over there, the white one
A: Ok. * Gives the pen*
T: *runs out, then runs in AGAIN**starts singing* Amma~~ No ink~~
A:Of course lah anair! You don't use a pen to write on wood!
T:*Argues* Then why I can write on it with a pencil?

If you do not understand, I've enlarge the word: pencil.
And then I stared for a few seconds....
Then it hit me, HARD
OF COURSE YOU CAN WRITE ON WOOD WITH A PENCIL!
YOU CAN WRITE WITH A PENCIL ON ANYTHING EXCEPT WATER, GENIUS!

I made gestures, whacking my forehead
Then my tuition-mate started laughing, while the others didn't
I realise that my tuition has no humour after that...
XD