Upvote:1
The Department of Immigration and Border Protection seem not to want to disclose the answer:
Your eVisitor lets you:
...
study in Australia for up to three months in some circumstances
However regarding an eVisitor Visa The Australian High Commission United Kingdom is not so mealymouthed:
You must not engage in any studies or training for more than three months.
And The Australian Visa Bureau confirms this:
Can I study in Australia on an ETA Visa?
Yes you can, but on an ETA visa you are only allowed to study for a maximum of three months. Students must, before commencing study, pass a chest X-ray examination carried out by a qualified radiologist.
ETA 601 and eVisitor 651 are essentially the same for an up to three months visit, other than cost and who is eligible for which.