What is the goal of the drop down?
I assume you want to select a Teacher in the dropdown. That selection must represent something.
If you want to relate the user with a teacher in Mendix, an association is used. Not using a association is possible by hacking around:
Consuming the referenced Teacher data
But as you see, that’s quite a hassle for something which is designed using the associations as we know in Mendix.
So my advise: use an association and unleash the power of Mendix.
Another advise: take the available learning paths to understand how Mendix works; https://academy.mendix.com/link/path/31/Become-a-Rapid-Developer
Use a datasource microflow to retrieve the values and return that list.