Cognitive Challenge in my Unit Plan

Cognitive Challenge in my Unit Plan
"They need to explore concepts, not just memorize them, engage in interesting and meaningful activities, not just drill-and-kill exercises." -- Annela Teemant
"If our students are going to understand, we have to slow down and uncover the curriculum." -- Jay McTighe

I am trying to frame activities that will cause my students to really think about how we put sentences together to communicate with each other. In this unit, students are presented background knowledge through interactive lecture/PowerPoint presentations. While listening and watching, they are asked to fill in the words and phrases left out of preprinted notes. They are also asked to respond and contribute, and complete brief practice exercises during this "lecture" portion of the classes.
Understanding is reinforced and assessed with various activities, quizzes, and games. They have opportunities to self-assess, and students have opportunities to teach other students.
The unit is couched in a spirit of playfulness. The students are being "sentenced" to work on sentences. They are assigned to "rehabilitate" problem "sentences" into complete, correct sentences that can then serve as upstanding citizens of the community of sentences.