Have students stand in two rows facing each other. Choose a question or problem from a worksheet and read it aloud to the class. Give students 30-60 seconds to discuss their responses and reasoning with the person across from them. Give a signal for each student to then move one position to the right (the student without a partner at the end simply walks to the other end to find his or her new partner.) Continue playing until students have discussed all the questions. giving students an answer, and have them work with their partner to brainstorm possible questions/problems for that answer. Challenge students to complete the worksheet and make an intentional error (an incorrect math calculation, out-of-order sequencing, grammatical or factual mistake in a written response, etc.) Then have students switch papers, mark the mistake, and discuss it.
Like other experienced teachers, I've taught the same concepts and skills to students so many times that I've developed a huge repertoire of activities that I can build into my instructional time. I have activities that provide more scaffolding if the kids didn't really seem to understand the lesson, and activities that will extend student learning if what I taught was too easy. I have activities that will take a long time if my lesson ends early, and activities that can be done quickly if my lesson takes too long.