$58K per year for 9 months work does, indeed convert to an annualized salary of $77.3K or almost exactly what you calculated.
I'm giving teachers the benefit of the doubt here. Even though the shorter work weeks, longer school vacations during the year and other perks does, indeed, translate to closer to eight months of work, better teachers put in time off the clock equivalent to at least one extra month. By no means all of them, of course, but a significant number.
Bottom line is while what Rush is saying isn't popular, it is true.
I used 8 months at $56/hr to get the $78k number, annualized it still sums to $116k full time.
$58k for 9 months is about $36/hr, a much more realistic figure that nets about $45k annual.
BLS $56/hr figure includes very highly compensated school administrators, or overvalued pension & benefit calculations.
I don't know what the pension payout is for a typical public school teacher, but hard to believe it equates to $20/hr average.