At Mondeto we recommend that you learn Esperanto in the process of teaching it to your class. You probably don't personally need more homework, right?
Still, everyone is different and maybe you'd rather do your own learning first. There are plenty of free online resources for you to do that, but here (->) is an old-school solution for those who might like to get a good overview of the scale of the language, and the reasons why the task is so finite.
The photo shows a bunch of Togolese refugees in a camp in Benin, West Africa. I don't speak a useful amount of French, let alone Ewe, and they didn't speak English, but they had taught themselves good Esperanto from a little book much like the one I'm giving you here.
I hope you like it!