The FAQ page of the parentteacheronline.com.au site confidently asserts that

We do not use cookies at all on our PTO site.

Oh really? Chrome inspector begs to differ.
This level of misstatement give me no level of confidence in one of the other assertions on their FAQ …

PTO maintains the highest level of Internet Security available. This means that any data entered into the system is as secure as information held by banks and large businesses.