The affidavit for the college exemption shall show that:

1. (a) The educational institution is of collegiate grade and is not conducted for profit.
2. (b) The grounds for which exemption is claimed are those within which its buildings are located.

3. (c) The property for which exemption is claimed is used exclusively for the purposes of education.

   Any additional proof of the facts stated may be required by the assessor.

   The exempt grounds need not be contiguous or in one tract.