Intro to Rails: Models
Active Record models are the core of many rails applications, and a little knowledge of how all the magic works goes a long way. We'll look at topics such as custom instance and class methods, model scopes, inheritance, code re-use/refactoring, custom validators, callbacks, and database connections.
This is an advanced beginner/intermediate level course. You should have Rails installed and be familiar with web programming using the MVC paradigm.
If you do not have Rails installed, check out Nitrous.IO, a web-based Ruby and Rails IDE