# World of Tan 24 - Clocks

Can you fit the tangram pieces into the outline of the clock?

## Problem

This activity follows on from World of Tan 23 - Transform This Into That.

It is the end of the week. The men have gone home and the children have returned from school and then gone out again with their friends. Mah Ling and Granma T are the only people left and they are busy 'doing the books'. It is late, and the first cold wind of November is blowing down the leaves.

**Mah Ling:**It's a lazy wind that's blowing under that door.

**Granma T:**What's that? I've never heard that phrase before.

**Mah Ling:**Oh, it's something that Leo and Leone taught me last year when they visited. The wind is so lazy - it blows through you and not round you.

**Granma T:**You're right, it feels like the wind is chilling my bones. But I am much older than you, Mah Ling, and I feel the cold more than I did as a younger woman.

**Mah Ling:**We're both getting older - it's amazing how time flies!

**Granma T:**Isn't that what Leo called "Tempus Fugit?"

**Mah Ling:**That's right! You know, it was a good idea to have those children from the International School to stay with us. Is anything happening this year?

**Granma T:**Little Ming and Little Fung went to visit Leo and Leone at their school in Hong Kong a few weeks ago. One day they hope to visit England with them.

**Mah Ling:**They're doing much more than I did when I was younger! I'd love to take the time to travel, to see another country, to see how other people live...

**Granma T:**Speaking of time, we must push on and finish those figures. I'll just write a quick note asking Wai Ping to put a strip over the gap at the bottom of the door, to block out the wind. We might as well have comfort as we get older...

In the meantime, complete the silhouette of the grandfather clock.

Extra activity:

- Have a go at this problem, using 7-minute and 11-minute sand timers to time some pasta which needs to cook for 15 minutes. What other times can you measure with these sand timers?

The story continues in World of Tan 25 - Pentominoes.

## Teachers' Resources

### Why do this problem?

This problem is an engaging context in which pupils can consolidate their knowledge of the properties of squares, triangles and parallelograms. By attempting this activity, children will be putting into practise their visualising skills, making guesses about where the different shapes might go before trying out their ideas. When combining the shapes to make the tangram, pupils will use their understanding of translations, reflections and rotations to decide how to transform each shape. There are also links between tangrams and fractions, and children can be encouraged to work out what fraction of the whole square is represented by each smaller shape.### Possible approach

Read this story with the whole class and look at the tangram as a group. Ask pupils to suggest where a shape might go. What transformation would be needed to move the shape into that position?When pupils are solving the tangram, they would benefit from working in pairs with a tablet or a printed copy of the shapes to cut out and move around. Working together will lead to rich discussions about the possible options for where each shape can go. When the children have solved the tangram, they can have a go at the extra activities.

At the end of the lesson, bring all of the pupils together and model the solution on the whiteboard. How does each shape need to be transformed? What fraction of the whole picture is each shape?

### Key questions

What could you put with this piece to make a square?Are all of the pieces different?

What's the smallest square you can make?

What has to go in that space? How do you know?