### Polydron

This activity investigates how you might make squares and pentominoes from Polydron.

### Multilink Cubes

If you had 36 cubes, what different cuboids could you make?

### Cereal Packets

How can you put five cereal packets together to make different shapes if you must put them face-to-face?

# Semaphore Signals

##### Stage: 2 Challenge Level:

Many of you sent in solutions to the first part of this question, correctly saying that the message reads "hello".

Yanqing who goes to Devonport High School for Girls wrote to say:

I think there are 7+6+5+4+3+2+1=28 ways altogether:
There are 8 possible positions for a flag but you can't put both flags in the same position, so when one of the flags is in position 1, there are 7 positions where you can put the second flag; when one of the flags is in position 2, because we have already counted "one flag in 1 and the other in 2", we have 6 new positions; when one of the flags are in position 3, we have 5 new positions; ... and so on.
When we get to: one of the flags is in position 8, all of the positions have already been counted, so we have: 7+6+5+4+3+2+1.

Well explained, Yanqing. Eva adds:

The 2 other combinations of directions are (NW, SE) and (N, NE).