the perfect tense "me" has not introduced before, only the past "li". so it seems strange to expect the students to know this!
Im wondering if it's a form of present progressive
This should help: https://www.swahilicheatsheet.com/
The tenses and examples are simplified using charts
What is the difference between wamekagua and walikagua
The tense marker, "me" is perfect tense, meaning that it has been completed, while "li" is past tense meaning that it occured in the past.