@liudr
I'm not sure if that works for every student. There are also students who don't have it in them... students who don't see the link between hardware and software, between an arduino board and your automatic parking system... So you need to help them A LOT ! taht doesn't mean they are not motivated...
I agree with millis to take small steps and don't get your hopes up to much 
I'm using the arduino to teach them electronics (Ohm's law, Volt, resistors, diodes,...) because you can actually let them put in practice what they've seen and read about. see previous post with courses...
Putting all together they will stay motivated because they know it could go everywhere with the arduinoboard. (car, parking system, webserver, lcd-screen, mini bots,...)
I promised them that we would create a small robot, but they don't know they will get thought electronics during the process XD
and now i'm going back to look at some tutorials 
Regards,
Stijn