I barter some work for my kids' school in exchange for tuition reduction. What form should I get from them to pay the taxes I owe on the barter transaction?

A secondary use of Form 1099-B is to report barter exchange transactions.

• A barter exchange is a network of people or companies who agree to trade property or services with one another without accepting payment in U.S. dollars.

Barter exchanges use Box 13 of the form to report the fair market value of all goods and services received by an individual member of the exchange over the course of a year. 

Income from bartering is taxable in the year it is performed. Bartering may result in liabilities for income tax, self-employment tax, employment tax or excise tax. Your barter activities may result in ordinary business income, capital gains or capital losses, or you may have a nondeductible personal loss.

The following links provide information you may find helpful:

IRS Tax Topic - Bartering

 Reporting Self-Employment Business Income and Deductions