The money allocated to a county board of education under this act shall be kept by such county board in a separate account to be known as the "free textbook account" and may be used for no other purpose except as otherwise provided by this section. Any balances being held in the "textbook aid account," as provided by law, are by this act authorized and directed to be transferred to said "free textbook account" to be used in accordance with the provisions of this act.

After complying with sections twenty-one-a and twenty-one-b of this article, the county board of education shall use any proceeds remaining in the "free textbook account" for the purchase (including replacement and repair) of textbooks for all pupils enrolled in the public schools of the county, grades one to eight inclusive, who are not provided with free textbooks under the requirements of sections twenty-one-a and twenty-one-b of said article. Such textbooks shall be those adopted by the state Board of Education for the elementary schools of the state.

The order of preference used in providing free textbooks for such pupils shall be either by grade preference in accordance with the plan as stated in subsection one below, or by subject preference in accordance with the plan as stated in subsection two below. The county board of education shall be required to adopt the one of these plans considered preferable for the county, and shall so advise the state Superintendent of Schools in writing before the plan so chosen is made operative through the requisition or purchase of textbooks in accordance therewith.

(1) In furnishing free textbooks by grade preference, the order of such preference shall be to begin with grade one and to continue by consecutive grades to and including grade eight.

(2) In furnishing free textbooks by subject preference, the order of such preference shall be to begin with the lowest grade and to continue by consecutive grades through grade eight as follows: Reading, arithmetic, history, health and elementary science, music, English, geography, writing, spelling, civics: Provided, That the order of subject preference as specified in subsection two above may be changed with prior approval of the state Board of Education, upon written application of any county stating reasons for wishing to make such change.

In any county in which the provisions of sections twenty-one-a, twenty-one-b, and twenty-one-d of this article shall have been fully complied with, any proceeds yet available in the "free textbook account" shall be used for the purchase of approved library books and other supplementary materials for grades one to eight: Provided, That such purchase shall have the prior approval of the state Board of Education.

In providing free textbooks to pupils under the provisions of this act, the county board of education shall have authority to purchase state-adopted textbooks from pupils who own them, or from their parents, at a price commensurate with the usable value of said books at the time, but in no case to exceed one half the original purchase price of the textbook to the pupil as determined by reference to the official contract price entered into between the publisher and the state Board of Education at the time of adoption of said textbook. All such purchases shall conform to the order of preference, either by grade or by subject, adopted by the county board of education under the provisions of subsection one and two above of this section for furnishing free textbooks to the pupils of said county.

Nothing in this act shall be construed to prevent a county board of education from supplementing its "free textbook account" with county school funds available for that purpose and so approved in the annual school budget.