Yes! Lessons range from the basic parts of speech (nouns, verbs, adjectives) all the way to the more complex (gerunds, participles, infinitives), so it is a program with topics that can be newly covered as the student develops and matriculates from one grade level to the next.

Since GrammarFlip is a comprehensive program with over 85 lessons, it would be up to each teacher (and department) to determine which lessons to cover at which grade levels within a school year based upon the appropriate developmental level of the students. 

Student data (ie, scores and writing) remains with the student's account, so each year a new teacher will be able to see the student's previous work and determine how well a student understands the material and whether or not to cover or review the concepts.  Because the learning levels of students are all across the board within a single classroom and grade level, students have access to all of the lessons and practice exercises at all times regardless of their grade level.