### Pebbles

Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

### It Figures

Suppose we allow ourselves to use three numbers less than 10 and multiply them together. How many different products can you find? How do you know you've got them all?

### Bracelets

Investigate the different shaped bracelets you could make from 18 different spherical beads. How do they compare if you use 24 beads?

# Crossings

##### Stage: 2 Challenge Level:

Remember that you must have two or more sticks to make a set.
Try starting with a set of $2$. How many sticks would be in the set placed across these $2$? How many crossings would that make?
If you can't have a set of $1$ stick, what number could you try next?
Do you notice anything about the number of sticks in each set and the number of crossings? How do these numbers relate to the total number of sticks?