This chapter explores the search for pedagogical equilibrium related to content knowledge. When teachers search for pedagogical equilibrium related to content knowledge, two main states of unrest were apparent: unrest associated with a lack of content knowledge; and, unrest due to competent understanding of content knowledge. The chapter firstly explores how teachers react when their content knowledge is lacking, which can be signalled by feelings of uncertainty, doubt and other negative or unrestful emotions. The second part of the chapter considers moments where teachers experience challenge to equilibrium due to well-developed content knowledge structures. A positive sense of enlightenment, enthusiasm and surprise can occur when teachers were able to capitalise on well-developed content knowledge structures enabling them to extend, link and contextualise the content in ways that benefit student learning. These situations are unrestful because teachers are unsure of how to capitalise on such moments. This positive sense of unrest is a novel finding of this research. Whether positive or negative, unrestful feelings stimulated teachers into action, either seeking to manage their challenge to equilibrium alone or with assistance from others.