Training Principles
The basic idea behind training is getting your rat to do a behaviour that is very similar to something they would naturally do and then reward them for doing it, associating the behaviour with a specific command word or sound. Repeated enough, and with enough patience, rats can quickly learn to do many different behaviours on command.
Anything a rat can learn to do must be something close to it's natural behaviour, and also something within it's physical and mental capabilities. A rat can climb, jump, stand on its hind legs, pull, and push, to name a few, but it cannot do things like cartwheels or math problems! Tricks you attempt to teach it must reflect these behaviours it can do, the more natural the behaviour the faster the rat will learn.
Coming When Called
The only thing I train every single one of my rats to do is to come when called. Not only is it cute, it is a good behaviour for them to have if they happen to escape their cage. To do this, I make a certain squeaking sound and when the rats come to the door of their cage, I reward them with food. I also make the sound every time it's feeding time, so they have come to associate the sound with "come here, you're getting food!" Click the video below to see one of my rats, Scurry, getting up from her nest and coming to the cage door when I call her.
Using this process, you can teach your rats to come to you from farther and farther distances by increasing the distance as they get better at coming to you. Even if they are very obedient, remember that rats still only listen when they want to and you should still never let your rat loose in a dangerous area or outside, as if it doesn't want to come back, it won't.
Another simple trick to teach is one rats do naturally, standing up on their hind legs. Start with your rat in a large enough area and show him a piece of food reward so he knows it is in your hand. Say your command word, such as "Up!", and raise the food upwards. Most rats will follow this food by standing up to try to grab it. When they do, give them the reward. Click the video below and to the left to see an example of training in progress for this trick.
If you keep repeating this procedure, your rat should eventually stand up whenever you say the command word, not just for the food. When they do, make sure you still give them the food when they have stood up. Click the video below and to the right to see what the finished trick looks like.
This is a very easy trick to teach and looks really impressive. First you will need to build the miniature 'bowling lane' (see photo, below). Any board can be used, but the example below was made with some scrap laminate flooring. Drill a small hole into one end of the board as shown, using a 1/2" or 1/4" drill bit. The hole doesn't have to go all the way through, just make a kind of divot where a small bit of food can be placed. Then make some gutter bumpers (optional) out of automobile weather stripping (rubber halfcircle lines that have an adhesive back). Take another small piece of weather stripping, or a small piece of wood, and attach it to the bottom of the board, towards the end where the hole is, so it will slant the board and make the ball roll easier. Don't have it slanted too much, though, or the ball will roll too fast and frighten the rat.
The next step is to find a small ball. It should be light and no more than 1" in diameter. There are some good miniature bowling sets out there on the internet, try doing a search. Put the treat in hole and put the ball on top of it, perhaps slightly off center so the rat can still see it. Put the rat by the lane, he should know by this point that there is a treat there, and will very likely go hunting for it, pushing the ball out of the way to do so. When he pushes the ball off the hole where it was resting, it will roll down the lane and knock over the pins!
Another way to teach this trick is to make the divot smaller, so it only just barely holds the ball in place. Put some baby food or other liquidy treat on the ball and the rat will go up to lick it and the motion should roll the ball towards the pins. The only downside to teaching it this way is that the rats often chase after the ball down the lane trying to get the rest of the food! The video below to the right shows this method, the video below to the left shows the previous method.