# Welcome to the new site - September 2012, Stage 4&5

Holidays over and back to school.... Welcome to our new site! Please update your bookmarks as you have reached the old monthly index page that will soon cease to exist.

## Problems

### Charlie's Delightful Machine

##### Stage: 3 and 4 Challenge Level:

Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?

### A Little Light Thinking

##### Stage: 4 Challenge Level:

Here is a machine with four coloured lights. Can you make two lights switch on at once? Three lights? All four lights?

### Mystic Rose

##### Stage: 4 Challenge Level:

Use the animation to help you work out how many lines are needed to draw mystic roses of different sizes.

### Summing Geometric Progressions

##### Stage: 4 and 5 Challenge Level:

Watch the video to see how to sum the sequence. Can you adapt the method to sum other sequences?

### Factors and Multiples Graphs

##### Stage: 4 and 5 Challenge Level:

Explore creating 'factors and multiples' graphs such that no lines joining the numbers cross

### Fix Me or Crush Me

##### Stage: 5 Challenge Level:

Can you make matrices which will fix one lucky vector and crush another to zero?

### Fundamental Particles Collection

##### Stage: 5 Challenge Level:

A collection of problems related to the mathematics of fundamental physics.