I have a couple to add:
1.) When my rex was a puppy he was very inteligent, I hadn't planned on teaching him much(everyone told me that huskies were very stuborn) but the 2 most important things sit and stay. And after he learnt those things, we stopped training, then one day I went to pet him and he put his arm on my hand, which gave me the start of teaching him shake a paw. After I taught him these 3 tricks/commands and saw how quickly he learned them I decided to keep going, I then taught him to speak(in which he will speak loudly if I say speak and lowly if I ask him to use his indoor voice). He then learned,look out the window, go to the door, go to your dish, and time for bed. But the one thing I couldn't teach him was to lie down... Until one day, I was telling him down and when he wouldn'T I started to get frustrated sighed and put my foot down on the floor(quite loudly) he automatically layed down I was amazed and in about 2 days he had it to a T andcould do it on command without me touching the floor. After that I taught him to roll over.
2.) What I am currently training him is quite difficult also. Where I live(the county I live in and not my house) there has been a few break ins last year and 1 about a week ago. Also people came to my house once at about 10oclock at night and walked around our property drunk. And when my parents leave they do lock the doors but sometimes are door does not lock properly. Therefore when I am home alone, I tend to stick pretty close to my dog(who is very protective of me despite being a husky). So I am teaching him to check all the rooms in our house for anyone. Like to day when I got home from school I was the only one home and when I went to get the key that is hidden outside it looked like someone had moved it so I took my dog opened all the doors and told him check, he'd then go in and look around and come back out, and for the most part he's doing pretty good, the only problem we have is the bathrooms and my parents room because usually he is not allowed in there I just have to show him he is only allowed in there if I invite him in.