I'm always interested in how things work. I never liked learning by memorizing steps, I prefer understanding them.
I hate learning on pure theory (e.g. math), I always need a point of reference on what I'm learning. Also, without an useful goal, learning has little motivation for me in itself. Studying math at university has been a huge challenge for me for many reasons, one of them being that it doesn't seem to be applicable to anything I do in life. They thought me how to derivate and integrate, but they didn't tell me how to make money with that knowledge. Learning how to use something to make money is the top priority in this world.
Also, I learn very much by doing things myself, or studying others' work. I'm always interested in reason why something was done in the way it's done. I think I also have a very keen sense of finding ways to improve something, as I seem to be able to find faults on everything. Of course, I do a lot of comparison based on my previous experiences with similar or even remotely similar things.
It helps me a lot when I can recognize a familiar pattern. "Hey, this thing works here the same way as A works in B."
I think these are clear signs of Si and Te at work.
I only support theories if they support my personal experiences.