I know it's possible to assign schools based on child or teen. I have two school lots in my town that I'd like to do that with.

I have SP mod, with Careers and school modules I believe they are called.

I just need a concise and easy to understand explanation on how to go about it. Step by step if possible.

Here's a pretty detailed explanation by igazor in an older thread: post64924#p64924
Hopefully that covers everything- the rest of the thread also goes over the fact it may take a few ingame days for the population to adjust to these rules. If you find it to be a little finicky, that's normal

Look here:

Education-Schools#My-school-is-crowded- ... congestion