Conclude by giving your students these challenges:

- A Tricky Length by MAA
- Pairs of Numbers by NRICH
- Corridors by NRICH
- Investigating the Dilution Series by NRICH
- Largest Common Divisor

Conclude by giving your students these challenges:

- A Tricky Length by MAA
- Pairs of Numbers by NRICH
- Corridors by NRICH
- Investigating the Dilution Series by NRICH
- Largest Common Divisor