Justification in using Edubuntu instead of Windows

[Isaiah]

I am the IT Director at a private elementary school. I converted the
majority of my schools computers over to Edubuntu during the course of the
summer after much research for an open source robust replacement for
Windows. They have been working perfectly once I figured out how to do what
I needed to do. I have given the Teachers basic training on how to utilize
the system. However, I am now hearing complaints from the teachers. Their
main complaint is that Edubuntu is not a good tool for the children to use
because it is not what is being used in the corporate world and everyday
life. They are under the impression that the children will be at a
disadvantage if they ever have to use a Windows environment. I, myself, can
come up with a number of reasons to discourage this type of reasoning, but I
was hoping to have some hard evidence to stand on. I would also love to have
some help from you guys/gals in eradicating this way of thinking. Are they
any numbers available as to how many school systems are using Edubuntu?

Thanks for your time.

Isaiah