### Two Clocks

These clocks have only one hand, but can you work out what time they are showing from the information?

### It's a Fence!

In this challenge, you will work in a group to investigate circular fences enclosing trees that are planted in square or triangular arrangements.

### Counting Cogs

Which pairs of cogs let the coloured tooth touch every tooth on the other cog? Which pairs do not let this happen? Why?

# Sorting the Numbers

##### Stage: 1 and 2 Challenge Level:

Well how about doing a simple jigsaw ?

This problem has been designed to be worked on in a group of about four. For more details about how you might go about doing this, please read the Teachers' Notes.

1. There are two jigsaw puzzles that your teacher can print out for you fromĀ here.pdf.

Complete each jigsaw and then put the pieces into the outline squares, which can be printed fromĀ here.pdf.

2. Place the smaller square of numbers on top of the other larger square in any way you like so that the small centimetre squares match up. (You may find it easier to copy the numbers on the smaller square onto a transparent sheet.)

3. Explore what happens when you add together the numbers that appear one on top of the other.

4. In your group, explore any other ideas that you come up with.

When you've looked at the thirty six combinations then you probably need to ask, "I wonder what would happen if we ...?". Change one small thing, explore that and then compare your two sets of results.

You might like to ask, "Why ...?".