How to create interesting Chinese lessons to older and more experienced colleagues?

Hi all, I'm a newbie here. I currently became a Chinese coach for Chinese Speaking Club at my company where most of my colleagues are older and more experienced than me and they know nothing about Chinese. The reason for this Chinese Speaking Club is to help them to learn to speak Chinese as fast as possible to support for their career. But it's very hard to teach a group of people like this. To be honest, this is my first time I challenge myself to be a Chinese coach. So I'm here, seeking for your advices to create interesting methods to teach them. If you have any idea, please let me know. I'm truly appreciated.