What should have been a peaceful tea break was transformed into a scene that could have been from your favourite pantomime.

Wai Ping and Wah Ming, two of the workmen at Granma T's were arguing with each other.

"It sticks out," said Wai Ping whose voice was getting louder.
"No it goes in," replied Wah Ming.

"Out"
"IN"
"It goes OUT I tell you"
"how many TIMES do you need telling it goes IN?"
"OUT"
"IN"
"OUT"
"In, I'll prove it! I shall ask the others."
"DO WHAT YOU LIKE - IT MEANS OUT - SO THERE"
"We'll see"

The last time such a scene had taken place between the cousins was when Wah Ming had wrongly believed that to ascend meant to go down.

Then as now, the argument went from one to another

"It's up."
"It's down."
"It's not, it's up."
and so on...

Mai Ling was the first to come in for her break and she was soon badgered by the workmen:

"Does it mean going in or sticking out?"

Haughtily she replied "It goes in like a cave, hence concave." Having experienced similar arguments she beat a hasty retreat to the sanctity of her office...peace and quiet was all she wanted.

Chi Wing (the foreman) was next in and he too was dragged into the argument. But, he couldn't for the life of him remember which was in and which was out. But he knew which way stalactites went and which way stalagmites grew. Sensing this did not help the argument, he took his tea and began carefully to study the schedule for the next day that had recently been pinned up. He didn't really want to be drawn in to yet another argument.

Granma T, who had quietly entered the room had foolishly asked how they both were. Their rude health was quickly confirmed and Wai Ping hurriedly asked, "Does concave meaning going inwards or outwards, in or OUT?"

Granma T swore that she would buy a dictionary next time she was in town because these arguments were getting too frequent. What was it last time? "When to use their and when to use there?". "Forget it", she thought. Without answering the question she too disappeared into Mai Ling's office and shut the door very firmly.

Only the children remained to be interrogated and they wouldn't be home from school yet.

Throughout the day the yard echoed to the cousins arguing.

So in the meantime while waiting for the children to settle the argument once and for all....

Children you may like to:

1. complete the silhouettes of two of the convex shapes that can be made;
2. find out what you can about the terms convex and concave. Find ways of explaining the ideas to your friend, family and teacher.
3. make a collection of things that are concave or convex or both;
4. invent an acrostic for both CONCAVE and for CONVEX
   (hint: Xray/ Xylophone/ Xmas..).

parents you may like to:

1. explain your understanding of the terms convex and concave and how you remember which is which;
2. form a collection of things from around the house that are convex/ concave in design;
   e.g. a empty cup - is this convex or concave or both? what about a full cup?
3. explore what happens when looking in convex/ concave mirrors
4. find other words that are often used to mean convex/ concave Can you find a 7 letter word for convex? 8 letter word for concave? etc..

teachers you may like to:

1. investigate the other 11 REMAINING convex figures that can be made using the tangram
2. explore when convex/ concave lens and mirrors are used and why?
3. explore more fully the mathematical definitions for convex and concave shapes (see below)
4. consider where terms like 'rude health' come from and try to list more that are similar
5. discuss in what other contexts animals are used to describe behaviour and other human characteristics? e.g. (Mai Ling) being badgered by the workmen horsing around! wolfing food down!......