In the northern hemisphere, many kids begin their school year in September. And September got to be called September because, until the Romans added the months of July (for Julius Caesar and August (for Augustus Caesar) to their ten-month calendar, this time of year was the seventh month and the word comes from the Roman word septem, meaning ‘seventh’. October, November, and December have the same origin, having once been the eighth (octo), ninth (novem) and tenth (decem) months. You’d think the powers that be (or were) would then have changed the names of those number months, but they didn’t, so kids might like to come up with the names they think those months should have had. Perhaps, for example, Autumna instead of September.
And, as regards the ‘ber’ bit: