Actually, this might be the site you are looking for. There are lots of real life problems looking for solutions right here at LQ.
If you do a web search for "linux tutorials," you will find a number of links, but I've not used any of them to be competent to judge. The first one I clicked wanted a java-enabled browser.
is good for flashcards learning; it offers a version for the major platforms, including Android. I have used if for several learning projects. There are a number of flashcard sets
already created for Linux.
. Machtelt Garrels's Intro to Linux was the most useful reference for me when I was first learning Linux.
There's a tremendous amount of information at The Linux Documentation Project
Hope this helps.