TUA uses only software legitimately acquired and complies with all accompanying licence conditions. If you are thinking of copying a program for your students, you need to check the licence conditions of the software to see if reproduction for teaching purposes is permitted.
Computer software is protected as a literary work under the Act, however the statutory educational licence explicitly excludes copying and communication of computer programs.
There are very limited opportunities for copying of software under exceptions in the Copyright Act. Nearly all developers release their software with some sort of licence for the end user. Most commercial software is purchased subject to a contractual agreement that limits copying or use to the specific purchaser. If it is open source, then the open source licence conditions dictate what can be done, and may be more permissive of copying for various purposes, but they still require the user to agree and abide by the conditions.