Hyphens

I thought I should explain how to use hyphens in my writing class. I pulled out my handy copy of Eats, Shoots, and Leaves by Lynne Truss for some catchy example:

"extra-marital sex
extra marital sex"

I had made a brief overhead for the purpose, and revealed this example first, as an attention-getter, and a way to make my main point. Of course they laughed, as I had hoped. I prepared to dig into hyphens: "You guys may laugh," I say, "but I see this every day! [pause] No, well, I mean, I, I see the lack of hyphen..."

By then, no one could hear me for the giggles. Class was five minutes from being over. But class was over.