Section 38. The accounting systems installed in accordance with this chapter shall be such as will, in the judgment of the director, be most effective in securing uniformity of classification in the accounts of such cities, towns and districts. The director may supply approximately at cost to cities, towns and districts where such accounting systems have been installed such books, forms or other supplies as may be required from time to time after the original installation of such systems. Such accounting systems and classifications, so far as they pertain to school committees, shall be subject to the advice and approval of the board of education.