Good morning, I am running a small scale apprentice style challenge with a group of  about 15 people.  We (the charity) will put £x into a kitty for each team and they are challenged to increase the amount over a period of 6 weeks.  Has anyone done anything like this before and would be happy to share their experience?  I'm particularly interested in any guidance notes for participants as well as an agreement that they guarantee to return the kitty amount.

Thanks in advance for any pointers 

Alex