Because you are a volunteer and not a paid educator who works at least 900 hours a year, you cannot use the above-the-line deduction of up to $250 from gross income (allowed even if you don’t itemize, assuming this break is extended for 2015). However, if you donate the supplies to the school and do not restrict their use, you can take a charitable contribution deduction for your out-of-pocket costs. To do this, you must (1) itemize your deductions, and (2) have obtained the required substantiation for these costs (including an acknowledgment from the school if the cost is $250 or more).
Depreciable property used in a trade or business and held for more than a year. All Section 1231 gains and losses are netted; a net gain is treated as capital gain, a net loss as an ordinary loss.