I needed to get a letter from my teacher training institute that listed how many days teaching practice I'd done and what age ranges. Took a few weeks of badgering the university but got there eventually! They included the names and addresses if both schools, the age of the students and how many days there on placement, it also include the start and end date as well as the title of the course. This was enough for AITSL when I applied 18 months ago.
All approved, got our 189 visa last May, validated visa this April and were off next January!
Good luck