If you need to learn/teach object orientation, these are my approaches (I hate that classic "car" example):

1) Keep in mind games like Warcraft, Starcraft, Civilization, Age of Empires (yes, I am old school). They are a good example of having classes to use, instantiating objects (creatures) and putting them to work together. As in a real system.

2) Think of your program as an office that has a job to do, or a factory that has something to deliver. Classes are the roles/jobs and objects are the workers/employees. They don't need to be complex, but their purpose must be really (really, really) well defined. Just like in a real office / factory.

3) Even better (or crazier), see your classes and objects as real beings, digital creatures in a abstract world, and yourself as a kind of god, who creates species (define classes) with wisdom. Give life when it is the time for them to come into the world (instantiate object) and kill them when they are done with their mission (dispose an object). Give them behavior, logic, conditions to work with, situations where they take action, and when they don't. Make them kinda "smart". Build them able to make decisions and take actions based on conditions. Give them life. Think on your program as an ecossystem. There must be balance, connection, species must be well defined and creatures must work together to achieve a common objective. Don't just throw code and pray for it to run. Plan it.

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When I talk about my classes like they are real beings, and programs as mini-worlds, some people say I am crazy, some others say that's passion.

It is both! @__@

In 3rd year of college my friend decided to get rid of all his NullPointerException by instantiating all his strings as "null"...

Scanner scanner = new Scanner(...);

Which is fine until you're in a corporation where the (many) classes are so detailed that each one is 30 chars long...

Trying to make my first genetic algorithm program "to be or not to be" in javascript.... (coming from java and experimenting a bit)
Can't even get past instantiating a function/class Gene.js file into the main.js file. -_-
I got a long way to go...

Re-instantiating the interesting bits from the other thing:

Time complexity of unsorted array equality operations. Go!

Say, you have a huge system with tight memory constraints. Almost every programmer who's created an instance of any object now has that instance in contention for resources on this system. The free memory is going lesser and lesser and other resources are also facing the heat. The garbage collector is not very effective (as garbage collectors we know are). There is a very large pool of objects that do not have any reference and are left to their own. Now instead of instantiating your own objects, you can simply request one off the pool and work with it however you like (regardless of what type the object was) and change its type to the type you want it to (coz they're all after all instances of the same base class).

Now the question is, would you still instantiate your own object or just request from the pool? If it were a fact that once this system is down, you'll never be able to develop and deploy a single program ever again, would you still not care for it?

If only my mom was a programmer, I could have easily explained why I want to adopt a kid and not make my own. :/

How the hell can a framework like Zend 3 have an instance of a class, this container, this service manager, that is basically responsible for instantiating everything but not have it accessible on a global level? Why do I have to create a factory class for every class that i intend to have access to this service manager? Zend is bull-fucking-shit.