In my regular classroom instruction I try to offer students new perspectives, including similes and other figurative models to get the ideas across. This is because I am very fond of similes, analogies, metaphors, and allegories. Here is an example of what I mean.
We could consider that reading an essay is a little bit like getting in a car (or a bus or a train, actually) and taking a trip. After all, both reading something and taking a trip have a clear beginnings and endings. In each case there will be some stopping points, some slightly more rapid sections, and helpful information along the way. Traffic signs provide that information for drivers, and punctuation does the same thing for readers.
A person reading sentences is like a driver traveling along a road. We always start on the left, drive to the right side of the paper or the screen, and then start again. Some roads start and end very simply, and not all that much happens in between. But it would be boring if the whole trip was like that; the mind prefers scenery and variety along the way. That’s what punctuation does: it’s a set of signs that guide the reader. The forms of punctuation help the reader understand complex ideas, by emphasizing the relationships of the ideas within the sentences. Punctuation tells readers when to do things – stop, pause, etc.
I hope that this idea will make sense to the students, and help them determine where to use punctuation marks. And the idea can go further: the student’s ideas are a car, and their actual writing skills are a road – or a bridge – on which the car travels. Sentences full of errors are like roads full of potholes, or even bridges with big holes. If this happens, the car of their ideas will not be able to reach its destination, which is the minds of other people. I tell them that if they want people to take them seriously then they might need to work on their roads (meaning, sentences), because most people don’t want to read writing that’s full of errors, which would mean that your ideas won’t get to the reader.
Fortunately, there is not a huge number of punctuation marks, and most writers can and will learn to make life easier for their readers.