Actually, my favorite (and possibly most successful) analogy for teaching is one that I use when teaching grammar, particularly sentence structure.
This analogy actually stems from the way that I think about grammar, the way I picture the sentences in my mind.
Each sentence is a drama or play with roles to be filled. Subject, Verb, Direct Object, Adjective, etcetera. Depending on the type of sentence, the roles may differ: Subject, Linking Verb, Predicate Adjective, Adverb . . .
The 8 Parts of Speech are the actors. Each of them has different abilities that determine which roles he is suited to play. And the director is pulling from the different groups of actors (for example, if a director is looking for an understudy for a noun that is playing the role of the Subject, he would have to get a nominative case pronoun–though that’s a pretty specific example that I usually save for later).
So, nouns can play any role and answers the question “Who?” or “What?”
Pronouns are understudies for nouns. They also make good extras (because they are less flashy than nouns so we don’t have to pay them as much attention).
Adjectives can play roles modifying nouns.
And so on . . . I make up the connections as I teach them sometimes.
Usually, though, I focus on the main roles in a sentence, and I give the students basic sentence patterns to start recognizing:
Subject-Action Verb-Direct Object
S-LV (state of being)
And then we work with real sentences, identifying the basic outline of the drama (the pattern) and then finding which part of speech has filled each role.
I find this analogy especially helpful in dealing with verbals. Verbs are the most versatile forms of speech because they can play almost any part of the sentence, in one form or another, but they’re pretty picky and may bring an entourage of their own personal assistants with them!
Baking a cake
Any baker will tell you that creating a successful confectionery demands his paying attention to a great many details, all of which can be compared to writing a successful critical essay:
baker's recipe = writer's outline
This is the overall blueprint which represents not only the desired end result of your efforts, but the exact way in which you will achieve that end. It includes the names and amounts of ingredients, directions on how to prepare, combine, and cook ingredients, and any other details necessary to the project. A writer's outline should offer an overall view of the project, carefully setting forth not only the arguments of the essay, but how those arguments will be argued.
good ingredients = supporting details
The baker's ingredients might include eggs, flour, milk, and sugar. The writer's ingredients might be details of plot and supporting quotations from the text. In neither case is it acceptable to plop down the ingredients and call it a finished product! You wouldn't call a bag of groceries a cake; don't call a collection of details an essay!
Take your raw material and make something of it!
Both bakers and writers must determine exactly how much room to devote to particular ingredients. In both cases, an ingredient might be essential, but too much of that one thing could ruin the cake. You can easily err in the other direction, too. Careful!
order of presentation of ingredients
A good recipe will tell the baker to keep dry ingredients separate from liquid, or in what order to add certain ingredients in the cooking process. A good writer will understand that it is not just the argument itself that can persuade, but the overall presentation that can augment or diminish the persuasiveness of the presentation. All writers should consider in what order to present his arguments - which to save for last, which to start off with. It can make a world of difference in the end.
how to mix the ingredients
A lot depends on the right method of mixing the ingredients together: sometimes the recipe calls for a gentle folding-in of ingredients, and sometimes you really have to mash stuff together using a blender! The same goes for writing an essay - determine the best and most persuasive way to present every argument. Is this a good place to paraphrase the text, or does this observation need a direct textual citation as support? Don't belabor a minor point, and don't leave a major point in chunks. Everything should be blended into the body of the essay appropriately, according to its nature.
After a cake is prepared according to the recipe, it needs to go in the oven, where everything comes together. The "baking time" of an essay can correspond to the time the writer devotes to crystallizing the ideas he has set forth in the course of the essay. If you don't bake it long enough, then you risk ending up with mush. If you keep it in too long, your reader will get indigestion. Spend just enough time at the end of your essay pulling together the threads of your argument...and then let it cool!
Every cook has his own secret ingredient that makes his concoction uniquely his own. Writers work that way, too, except with writers it is more a question of style than anything else.
an appetizing end result
A nice presentation caps a baker's effort. Make your essay look like it is worth reading (neat, proofed), just like any good cake looks like it is worth eating.