At the election the ballots shall contain the words "for the bonds" and "against the bonds". To the right of and opposite each proposal shall be placed a square approximately the size of the square placed opposite the names of candidates on ballots. The voter shall indicate his vote "for the bonds" or "against the bonds" by inserting the mark "X" in the appropriate square. No other question, word or figure need be printed on any ballot. The ballot need not be any particular size, nor need sample ballots be printed, posted or distributed.