Duolingo

Duolingo is one of the Online Courses to Learn Grammar. One of the most crucial aspects of learning a new language is studying grammar, and Duolingo's methodology effortlessly blends grammar courses into the overall language learning process. Rather than teaching a separate "grammar" course, Duolingo combines grammar lessons with vocabulary and other practice skills courses. It's an efficient strategy to keep adult learners focused on a second (or even third) language, which is the site's primary audience.

The framework of Duolingo is built on a skill "tree," with new ones unlocked when previous ones are mastered through practice tasks. It also allows (and actively encourages) students to repeat previous subjects in order to stay sharp, as well as spend as much or as little time on classes as they like. At the time of release, the site offered around 37 languages, including Indigenous languages, all of which were absolutely free.