Restricting Write Access to USB

[BillHicksRIP]

I need to share a Windows 7 Home Premium and a Windows 7 Pro laptop with some colleagues but I need to be able to prevent them from inserting a USB and writing to it. There's a couple of things I need to work on with them but not run off with by inserting a USB stick and running off with it. Any ideas for a simple solution?

Thanks

 

[BillHicksRIP]

Should have said, the laptops will be off the network and have never been part of a domain. I'm doing some training for a 3rd party and dont want them running off with my material, presentations etc.