This chapter examines two types of response technologies (selected and constructed) available to support discussion and participation in the classroom, and describes our experiences using and observing them in a variety of mathematics, science, and computer science classes at various educational levels. Selected response systems (a.k.a., clickers) display multiple-choice questions, and then collect and analyze student responses, and present distribution summaries to the class. Constructed response systems allow students to use handheld computers to generate free-form graphical responses to teacher prompts using various software applications. Once completed, students submit their responses to the instructor’s computer wirelessly. The instructor may then select and anonymously project these authentic student work samples or representations to promote classroom discussion. We review the purpose, design, and features of these two types of response systems, highlight some of the issues underlying their application, discuss our experiences using them in the classroom, and make recommendations.