The Pali Primer is a publication of the Vipassana Research Institute. It aims to provide an elementary understanding of the Pali language.
See also Pali Primer video lessons by Bhante Suddhāso:
https://www.youtube.com/playlist?list=PLfYRXXbgoIy_jI5cWYEfaXENMH3HbPY_W
Another edition:
http://www.pratyeka.org/Silva/
Answer key:
https://www.tipitaka.net/pali/palidd/
Memory cards:
https://www.memrise.com/course/381556/pali-primer-vocabulary-de-silva/