Once you have several tasks shaped, you will want to look at teaching your dog more complex tasks, that incorporate the shaped behaviors into chains or sequences. These two ways sound similar but they are quite different ways of training.
Chaining, is about putting together several behaviors that always occur in the same order and ultimately become one behavior cued with a single cue. Each behavior may become the cue for the next behavior and there can be external cues such as your body language, verbal cues or equipment. A retrieve is actually a very complicated example. Your dog must do a series of behaviors all blended into one to do a retrieve. In this case, we use a “back chain” instead of a chain so we start with the last behavior the dog is expected to do and work forwards to the first behavior. That way, we are always asking the dog to move towards a behavior they know really well. For those in dog sports, fly ball is a chained behavior.
Switching off a light by jumping on a chair is a behavior chain. Here is how you would put a simple chain together that results in that single cued behavior. The video starts with shaping the actual switch flip behavior, then moves into adding height, adding the chair and finally putting the chain together and cueing it as a single behavior.
Sequencing, on the other hand, is when you put a series of behaviors together but the order is changeable or not in a predictable series. An example of this would be: when your dog helps you put on your coat, opens the door, holds it as you pass through, closes the door, and pulls your wheelchair to the top of the ramp, and hops into your vehicle ahead of you as you raise the ramp. For those who enjoy dog sports, agility is a sequenced behavior. Each behavior in the sequence is cued (either by physcial presence of an object, hand signal or verbal cue).
We use both to train assistance dogs. Sometimes a chained behavior (such as retrieving) can be part of a sequence too! For example, in the morning, your dog goes to get the newspaper from the mail slot, brings it to you, then runs and wakes up your child so she can eat breakfast. Next, she might bring you your shoes to put on and take your slippers back to the closet.
Here’s a great article that goes into more detail about the differences and how to use them.
So I am I addressing this here? Because it is important for us to realize how complex a task we may be asking our dogs to do and how we must be careful to reward appropriately for each task based on the complexity or length of it, especially in the early stages of training. Later, we can wean him/her off the treats and/or substitute other rewards but we must be diligent about rewarding for each step of the training to keep our dogs eager to work with us.