I have a quick point. Employer verification of expenses is essential to the operation of the income tax code. Otherwise it would create a very slippery slope and lead to a very bad precedent for other employment expense claims. It is just to keep everybody honest across the board, to ensure when teachers do submit their supply tax credit that it is verified by their employers. This happens not only in the teaching industry, but in every industry.
The government has done a great thing to ensure that teachers who do make students' lives a bit easier when they are teaching get this tax credit, but to keep everybody honest, it should be verified by the employer.