During the 30 days next preceding a general primary or election or during the ten days next preceding a special primary or election, the superintendent shall place on public exhibition, in such public places and at such times as he or she may deem most suitable for the information and instruction of the electors, one or more sets of sample ballots that will be used in such election. The sample ballots shall show the offices and questions to be voted upon, the names and arrangements of parties and bodies, and the names and arrangements of the candidates to be voted for. Such ballots shall be under the charge and care of a person competent as an instructor.