Specialized industries (forestry, mining, etc) require relatively uneducated workers. Unfortunately, I placed a strong emphasis on education in my city, and over half the population (including children) have university degrees. Not really suitable for doing grunt work.
So if my education system is so top notch, how do I attract the uneducated folk to my fine city so that they can work the mines?
I think you are under the assumption that Highly Educated Workers cannot work the Uneducated jobs.
They indeed will eventually fill whatever jobs are available. At first they may not want to go work there, and the dirty industries may complain when they first go into business that there are no workers, but the Highly Educated will eventually go work there. The industry itself will display that they are "overeducated" — which doesn't appear to impact its performance any. So feel free to send those university degree children to the mines :D
Of course, theoretically if they went to work these lower jobs and you had some Highly Educated positions somewhere else, they wouldn't be available for those jobs. But then again you have no real way to control of who-works-where anyway.
You should be able to operate these industries fine with educated workers. Have some residential zone laid down out of range of any education facilities, but within the range of the industries you want them to staff.
You can use the view modes in the top right (or by selecting the education panel) to see how far your education reaches your city, your residential buildings should be red if they're out of range.
Just separate your industrial zone from everything else and then put houses a stones throw from it! Then make sure that education is very far away from them.
Level 3 industrial requires more educated workers than level 1 industrial (the building will show the breakdown required when selected). Be sure to add cargo trains and public transit to help it level up, as well as other services.
For specialized industries I'm not sure how it differs.
