"not including on Sch C would result in -0- income for the year."
If you have no business income and no business expenses for the year, then you can just omit Schedule C from your tax return.
You might have expenses for your side business, not related to your W-2 employment. For example, you might have spent money on advertising to try to get outside work. If so, you can file Schedule C and show a loss.
But any expenses related to the additional work you did for the district are employee expenses and, under the new tax law, are not deductible.
