I don’t know how I am going to translate this sentence from Unit 7. I think it’s related to the conditional sentences with relative protases and it seems like an optative+optative, future less vivid conditional sentence, but still it doesn’t make any sense.
αἰσχρὰ ἂν πράττοιτε οἳ τοὺς τῆς οἰκίᾱς ποιήματα μὴ διδάσκοισθε.
What really confuses me here is the nominative masculine plural relative pronoun “hoi” since both verbs are conjugated as second person plural.
Any ideas?
“conditional sentences with relative protases” – That’s what this is. The (understood) antecedent of the relative clause beginning with οἳ is ὑμεῖς.
"You who . . . " or “If you should not . . . you would not.”
If you should not teach men in the house poems, you would be doing bad things.
That makes sense now. Thank you. 
Two (minor) observations regarding that translation.
You have it simply as a future less vivid, without regard for the (general) force of that relative protasis. I think it would be better as, “if any of you…”, or “whoever of you…”. (HQ discusses this on p. 176-77.)
διδάσκοισθε is, obviously, present MIDDLE. And that middle voice has a causative force, so that it’s not simply “teach” but rather “cause (someone) to be taught”. (HQ p. 168)
Hope this helps.